Periodic Table Map

H

1

1.008

1s1

Hydrogen

Year discovered1766
Standard stategas
Melting point (K)14
Boiling point (K)20
Density (g/cm3)0.0000899
Key Isotopes1H, 2H
Oxidization States-1, 1
Electronegativity2.2
Atomic Radius (pm)37
Ionization Energy (kJ/mol)1312
Image of Hydrogen

By Images of Elements [ CC BY 3.0 ]

Vial of glowing ultra pure hydrogen, H2.

Although hydrogen was prepared many years earlier, it was first recognized as a substance distinct from other flammable gases in 1766 by Henry Cavendish, who is credited with its discovery; it was named by Antoine Lavoisier in 1783.

He

2

4.003

1s2

Helium

Year discovered1868
Standard stategas
Melting point (K)0.95
Boiling point (K)4
Density (g/cm3)0.0001785
Key Isotopes4He
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)32
Ionization Energy (kJ/mol)2372
Image of Helium

By Images of Elements [ CC BY 3.0 ]

Vial of glowing ultra pure Helium.

A French astronomer, Pierre-Jules-César Janssen, first discovered helium during the solar eclipse of 1868 in India when he detected a yellow line (587.49 nm) in the solar spectrum very close to the yellow sodium D-line. For many years helium was regarded as an element that might exist on the sun although it was unknown on the Earth.

Li

3

6.941

[He] 2s1

Lithium

Year discovered1817
Standard statesolid
Melting point (K)454
Boiling point (K)1615
Density (g/cm3)0.535
Key Isotopes7Li
Oxidization States1
Electronegativity0.98
Atomic Radius (pm)134
Ionization Energy (kJ/mol)520
Image of Lithium

By Dennis "S.K" [ CC BY 3.0 ]

Lithium metal pieces. 99.9%.

Lithium was discovered by Johan August Arfvedson in 1817 during an analysis of petalite ore, an ore now recognised to be LiAl(Si2O5)2, taken from the Swedish island of Utö. Arfvedson subsequently discovered lithium in the minerals spodumene and lepidolite. C.G. Gmelin observed in 1818 that lithium salts colour flames bright red.

Be

4

9.012

[He] 2s2

Beryllium

Year discovered1798
Standard statesolid
Melting point (K)1560
Boiling point (K)2743
Density (g/cm3)1.848
Key Isotopes9Be
Oxidization States2
Electronegativity1.57
Atomic Radius (pm)90
Ionization Energy (kJ/mol)900
Image of Beryllium

By Images of Elements [ CC BY 3.0 ]

Pure beryllium bead, 2.5 grams.

The element was recognised by Louis Nicolas Vauquelin in 1798 in beryl and emeralds. The metal was isolated much later on in 1828 by Friedrich_Wöhler (and independently by Antoine Bussy) by the action of potassium on BeCl2 in a platinum crucible. Beryl were both known to early Egyptians but it was not realised until the end of the 18th century

B

5

10.811

[He] 2s22p1

Boron

Year discovered1807
Standard statesolid
Melting point (K)2348
Boiling point (K)4273
Density (g/cm3)2.46
Key Isotopes11B
Oxidization States1, 2, 3
Electronegativity2.04
Atomic Radius (pm)82
Ionization Energy (kJ/mol)801
Image of Boron

By James L Marshall [ CC BY 3.0 ]

Polycrystalline chunks of rhombohedral β-boron, net 25.5 grams.

Boron was first isolated in England in 1807 by Sir Humphry Davy and then in France in 1808 by Joseph Louis Gay-Lussac and Louis Jacques Thénard. It occurs also in the mineral. Boron does not occur free in nature. Large deposits of borax, kermite, colemanite, and other boron minerals are found in the arid regions of the W United States

C

6

12.011

[He] 2s22p2

Carbon

Year discoveredAncient
Standard statesolid
Melting point (K)3823
Boiling point (K)4300
Density (g/cm3)2.26
Key Isotopes12C, 13C, 14C
Oxidization States-4, -3, -2, -1, 1, 2, 3, 4
Electronegativity2.55
Atomic Radius (pm)77
Ionization Energy (kJ/mol)1087
Image of Carbon

By Robert Lavinsky [ CC BY SA 3.0 ]

Diamond and graphite shown side by side.

Carbon as charcoal, soot and coal has been used since prehistoric times. Carbon as diamond has also been known since very ancient times. The recognition that soot (amorphous carbon), graphite (another form of carbon) and diamond are all forms of carbon.

N

7

14.007

[He] 2s22p3

Nitrogen

Year discovered1772
Standard stategas
Melting point (K)63
Boiling point (K)77
Density (g/cm3)0.001251
Key Isotopes14N
Oxidization States-3, -2, -1, 1, 2, 3, 4, 5
Electronegativity3.04
Atomic Radius (pm)75
Ionization Energy (kJ/mol)1402
Image of Nitrogen

By Alchemist-hp [ CC BY 3.0 ]

Spectrum = gas discharge tube filled with nitrogen N2. Used with 1,8kV, 18mA, 35kHz. ≈8" length.

It was known during the 18th century that air contains at least two gases, one of which is oxygen which supports combustion and life, and the other was nitrogen which does not. Nitrogen was discovered by Daniel Rutherford in 1772, who called it noxious air.

O

8

15.999

[He] 2s22p4

Oxygen

Year discovered1774
Standard stategas
Melting point (K)55
Boiling point (K)90
Density (g/cm3)0.001429
Key Isotopes16O
Oxidization States-2, -1, 1, 2
Electronegativity3.44
Atomic Radius (pm)73
Ionization Energy (kJ/mol)1314
Image of Oxygen

By Alchemist-hp [ FAL ]

Spectrum = gas discharge tube filled with oxygen O2. Used with 1,8kV, 18mA, 35kHz. ≈8" length.

Leonardo da Vinci suggested that air consists of at least two different gases and of these one of the gas supported flames and life. Oxygen was prepared by several workers before 1772 but these workers did not recognize it as an element. Joseph Priestley is generally credited with its discovery (who made oxygen by heating lead or mercury oxides).

F

9

18.998

[He] 2s22p5

Fluorine

Year discovered1670
Standard stategas
Melting point (K)54
Boiling point (K)85
Density (g/cm3)0.001696
Key Isotopes19F
Oxidization States-1
Electronegativity3.98
Atomic Radius (pm)71
Ionization Energy (kJ/mol)1681
Image of Fluorine

By Prof B. G. Mueller [ CC BY SA 3.0 ]

A tube with liquid fluorine in a cryogenic bath.

In 1670 a recipe containing calcium fluoride, CaF2 was used to etch glass. It seems that George Gore made a little fluorine through an electrolytic process but his apparatus exploded when the fluorine produced reacted with hydrogen from the other electrode. The element finally was isolated in 1886 by Ferdinand Frederic Henri Moisson.

Ne

10

20.18

[He] 2s22p6

Neon

Year discovered1898
Standard stategas
Melting point (K)25
Boiling point (K)27
Density (g/cm3)0.0009
Key Isotopes20Ne
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)69
Ionization Energy (kJ/mol)2081
Image of Neon

By Alchemist-hp [ CC BY NC ND 3.0 ]

Spectrum = gas discharge tube: the noble gas: neon Ne. Used with 1,8kV, 18mA, 35kHz. ≈8" length.

Neon was discovered by Sir William Ramsay and Morris Travers in 1898 very shortly after their discovery of the element krypton. Both elements were discovered through work on liquid air

Na

11

22.99

[Ne] 3s1

Sodium

Year discovered1807
Standard statesolid
Melting point (K)371
Boiling point (K)1156
Density (g/cm3)0.968
Key Isotopes23Na
Oxidization States-1, 1
Electronegativity0.93
Atomic Radius (pm)154
Ionization Energy (kJ/mol)496
Image of Sodium

By Dennis "S.K" [ CC BY SA 3.0 ]

Sodium metal pieces. 99.5%.

Until the 18th century no distinction was made between potassium and sodium. Sodium was first isolated in 1807 by Sir Humphry Davy, who made it by the electrolysis of very dry molten sodium hydroxide, NaOH. Sodium was collected at the cathode. Shortly after Gay-Lussac isolated sodium by reducing caustic soda with iron metal at high temperatures.

Mg

12

24.305

[Ne] 3s2

Magnesium

Year discovered1808
Standard statesolid
Melting point (K)923
Boiling point (K)1363
Density (g/cm3)1.738
Key Isotopes24Mg
Oxidization States1, 2
Electronegativity1.31
Atomic Radius (pm)130
Ionization Energy (kJ/mol)738
Image of Magnesium

By Images of Elements [ CC BY 3.0 ]

Magnesium crystal.

In 1808, Sir Humphry Davy discovered magnesium in its oxide, although it is not certain that he isolated the metal. Pure magnesium was isolated substantially by Antoine Bussy in 1828 by chemical reduction of the chloride. Magnesium was first isolated electrolytically by Michael Faraday in 1833.

Al

13

26.982

[Ne] 3s23p1

Aluminium

Year discoveredAncient
Standard statesolid
Melting point (K)933
Boiling point (K)2792
Density (g/cm3)2.7
Key Isotopes27Al
Oxidization States1, 3
Electronegativity1.61
Atomic Radius (pm)118
Ionization Energy (kJ/mol)578
Image of Aluminium

By Images of Elements [ CC BY 3.0 ]

Chunk of aluminium, 2.6 grams, 1 x 2 cm.

The ancient Greeks and Romans used alum in medicine as an astringent, and in dyeing processes. In 1761 de Morveau proposed the name "alumine" for the base in alum. In 1807, Davy proposed the name alumium for the metal, undiscovered at that time, and later agreed to change it to aluminum.

Si

14

28.085

[Ne] 3s23p2

Silicon

Year discovered1854
Standard statesolid
Melting point (K)1687
Boiling point (K)3173
Density (g/cm3)2.33
Key Isotopes28Si, 30Si
Oxidization States-4, -3, -2, -1, 1, 2, 3, 4
Electronegativity1.9
Atomic Radius (pm)111
Ionization Energy (kJ/mol)787
Image of Silicon

By Enricoros [ Public Domain ]

Close up photo of a piece of purified silicon.

Jöns Jacob Berzelius is generally credited with the discovery of silicon in 1824. Deville prepared crystalline silicon in 1854, a second allotropic form of the element.

P

15

30.974

[Ne] 3s23p3

Phosphorus

Year discovered1669
Standard statesolid
Melting point (K)317
Boiling point (K)554
Density (g/cm3)1.823
Key Isotopes31P
Oxidization States-3, -2, -1, 1, 2, 3, 4, 5
Electronegativity2.19
Atomic Radius (pm)106
Ionization Energy (kJ/mol)1012
Image of Phosphorus

By Images of Elements [ CC BY 3.0 ]

Red phosphorus as powder.

Phosphorus was discovered in 1669 by Hennig Brand, who prepared it from urine. Not less than 50-60 buckets per experiment in fact, each of which required more than a fortnight to complete.

S

16

32.065

[Ne] 3s23p4

Sulfur

Year discoveredAncient
Standard statesolid
Melting point (K)388
Boiling point (K)718
Density (g/cm3)1.96
Key Isotopes32S
Oxidization States-2, -1, 1, 2, 3, 4, 5, 6
Electronegativity2.58
Atomic Radius (pm)102
Ionization Energy (kJ/mol)1000
Image of Sulfur

By Ben Mills [ Public Domain ]

A sample of sulfur.

Sulphur was known in ancient times and referred to in Genesis as brimstone. Assyrian texts dated around 700-600 BC refer to it as the "product of the riverside," where deposits could be found. In the 9th century BC, Homer mentioned "pest-averting sulphur."

Cl

17

35.453

[Ne] 3s23p5

Chlorine

Year discovered1774
Standard stategas
Melting point (K)172
Boiling point (K)239
Density (g/cm3)0.003214
Key Isotopes35Cl, 37Cl
Oxidization States-1, 1, 2, 3, 4, 5, 6, 7
Electronegativity3.16
Atomic Radius (pm)99
Ionization Energy (kJ/mol)1251
Image of Chlorine

By W. Oelen [ CC BY SA 3.0 ]

Chlorine gas in an ampule.

Chlorine was discovered in 1774 by Carl Wilhelm Scheele, who thought it was a compound of oxygen; it was named and identified as an element by Sir Humphry Davy in 1810.Chlorine is a greenish-yellow poisonous gas with a disagreeable, suffocating odor; it is about two and one-half times as dense as air

Ar

18

39.948

[Ne] 3s23p6

Argon

Year discovered1894
Standard stategas
Melting point (K)84
Boiling point (K)87
Density (g/cm3)0.001784
Key Isotopes40Ar
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)97
Ionization Energy (kJ/mol)1521
Image of Argon

By Alchemist-hp [ CC BY NC ND 3.0 ]

Spectrum = gas discharge tube: the noble gas: argon Ar. Used with 1,8kV, 18mA, 35kHz. ≈8" length.

Argon was first obtained by Lord Rayleigh and Sir William Ramsay in 1894. Previously Lord Rayleigh had noticed that a liter of supposedly pure nitrogen drawn from the air weighed more than a liter prepared from a nitrogen compound. This difference in weight led him to conclude that another gas was present in the supposedly pure nitrogen

K

19

39.098

[Ar] 4s1

Potassium

Year discovered1807
Standard statesolid
Melting point (K)337
Boiling point (K)1032
Density (g/cm3)0.856
Key Isotopes39K
Oxidization States1
Electronegativity0.82
Atomic Radius (pm)196
Ionization Energy (kJ/mol)419
Image of Potassium

By Dennis "S.K" [ CC BY 3.0 ]

Potassium metal pieces. 99.9%.

Potassium was discovered in 1807 by Humphry Davy, who decomposed potash with an electric current. Potassium was the first metal so discovered; Davy discovered sodium a few days later by a similar experiment.

Ca

20

40.078

[Ar] 4s2

Calcium

Year discoveredAncient
Standard statesolid
Melting point (K)1115
Boiling point (K)1757
Density (g/cm3)1.55
Key Isotopes40Ca
Oxidization States2
Electronegativity1
Atomic Radius (pm)174
Ionization Energy (kJ/mol)590
Image of Calcium

By Matthias Zepper [ Public Domain ]

Pure calcium in a protective argon atmosphere.

Compounds such as lime (CaO, calcium oxide) were prepared by the Romans in the first century under the name calx. Literature dating back to about 975 AD notes that plaster of paris (calcium sulphate, CaSO4, dehydrated gypsum) is useful for setting broken bones. Calcium metal was not isolated until 1808.

Sc

21

44.956

[Ar] 3d14s2

Scandium

Year discovered1876
Standard statesolid
Melting point (K)1814
Boiling point (K)3103
Density (g/cm3)2.985
Key Isotopes45Sc
Oxidization States1, 2, 3
Electronegativity1.36
Atomic Radius (pm)144
Ionization Energy (kJ/mol)633
Image of Scandium

By Alchemist-3.0 [ CC BY NC ND 3.0 ]

Scandium, sublimed-dendritic, high purity 99.998 % Sc/TREM. As well as an argon arc remelted 1 cm3 scandium cube for comparison.

Scandium was discovered by Lars Frederick Nilson in the minerals euxenite and gadolinite, which had not yet been found anywhere except in Scandinavia. He was actually looking for rare earth metals. By processing 10 kg of euxenite and other residues of rare-earth minerals, he was able to prepare about 2 g of scandium oxide of high purity.

Ti

22

47.867

[Ar] 3d24s2

Titanium

Year discovered1791
Standard statesolid
Melting point (K)1941
Boiling point (K)3560
Density (g/cm3)4.507
Key Isotopes48Ti
Oxidization States-1, 2, 3, 4
Electronegativity1.54
Atomic Radius (pm)136
Ionization Energy (kJ/mol)659
Image of Titanium

By Images of Elements [ CC BY 3.0 ]

Titanium crystal made with the van Arkel-de Boer process. 87 grams, original size in cm: 2.5 x 4.

Titanium was discovered by the Reverend William Gregor in 1791, who was interested in minerals. He recognized the presence of a new element, now known as titanium, in menachanite, a mineral named after Menaccan in Cornwall (England). Several years later, the element was rediscovered in the ore rutile by a German chemist, Klaproth.

V

23

50.941

[Ar] 3d34s2

Vanadium

Year discovered1803
Standard statesolid
Melting point (K)2183
Boiling point (K)3680
Density (g/cm3)6.11
Key Isotopes51V
Oxidization States-1, 2, 3, 4
Electronegativity1.63
Atomic Radius (pm)125
Ionization Energy (kJ/mol)651
Image of Vanadium

By Images of Elements [ CC BY 3.0 ]

2.3 grams pure vanadium pieces with a colored oxide layer. Size of the largest piece in cm: 0.7 x 0.7.

The discovery of vanadium happened "twice." The discovery of vanadium was claimed first by Andres Manuel del Rio (a Spanish mineralogist) at Mexico City in 1803. In 1831, Nils Gabriel Sefström was working with some iron ores and was able to isolate a new oxide. This lead to the element being named in honour of the Germanic tribes' goddess Vanadis

Cr

24

51.996

[Ar] 3d54s1

Chromium

Year discoveredAncient
Standard statesolid
Melting point (K)2180
Boiling point (K)2944
Density (g/cm3)7.14
Key Isotopes52Cr
Oxidization States-2, -1, 1, 2, 3, 4, 5, 6
Electronegativity1.66
Atomic Radius (pm)127
Ionization Energy (kJ/mol)653
Image of Chromium

By Alchemist-hp [ CC BY NC ND 3.0 ]

High purity (99.999 % = 5N) chromium crystals, produced by chemical transport reaction through decomposition of chromium iodides, as well as a high purity (99,95 % = 3N5) 1 cm3 chromium cube for comparison.

In the mid 18th century analysis of Siberian "red lead" (PbCrO4, crocoite) from Siberia showed that it contained quite a lot of lead, but also a further material. This was eventually identified as chromium oxide. Chromium oxide was discovered in 1797 by Louis-Nicholas Vauquelin, who prepared the metal itself in the following year.

Mn

25

54.938

[Ar] 3d54s2

Manganese

Year discovered1774
Standard statesolid
Melting point (K)1519
Boiling point (K)2334
Density (g/cm3)7.47
Key Isotopes55Mn
Oxidization States-3, -2, -1, 1, 2, 3, 4, 5, 6, 7
Electronegativity1.55
Atomic Radius (pm)139
Ionization Energy (kJ/mol)717
Image of Manganese

By Tomihahndorf [ CC BY SA 3.0 ]

Manganese.

Manganese metal was isolated by Johan Gottlieb Gahn in 1774. He reduced the dioxide (MnO2, as the mineral pyrolusite) with charcoal (essentially carbon) by heating and the result was a sample of the metal manganese.

Fe

26

55.845

[Ar] 3d64s2

Iron

Year discoveredAncient
Standard statesolid
Melting point (K)1811
Boiling point (K)3134
Density (g/cm3)7.874
Key Isotopes56Fe
Oxidization States-2, -1, 1, 2, 3, 4, 5, 6
Electronegativity1.83
Atomic Radius (pm)125
Ionization Energy (kJ/mol)763
Image of Iron

By Pics About Space

Iron meteorite.

Iron is an abundant element in the universe; it is found in many stars, including the sun. Iron is the fourth most abundant element in the earth's crust, of which it constitutes about 5% by weight, and is believed to be the major component of the earth's core.

Co

27

58.933

[Ar] 3d74s2

Cobalt

Year discoveredAncient
Standard statesolid
Melting point (K)1768
Boiling point (K)3200
Density (g/cm3)8.9
Key Isotopes59Co
Oxidization States-1, 1, 2, 3, 4, 5
Electronegativity1.88
Atomic Radius (pm)126
Ionization Energy (kJ/mol)760
Image of Cobalt

By Images of Elements [ CC BY 3.0 ]

3 gram piece of cobalt.

Minerals containing cobalt were of value to the early civilisations of Egypt and Mesopotamia for colouring glass deep blue. Cobalt was announced to be an element by Georg Brandt about 1739 (or possibly 1735). He had been trying to demonstrate that the blue colour of glass was because of a new element, cobalt

Ni

28

58.693

[Ar] 3d84s2

Nickel

Year discovered1751
Standard statesolid
Melting point (K)1728
Boiling point (K)3186
Density (g/cm3)8.908
Key Isotopes58Ni
Oxidization States-1, 1, 2, 3, 4
Electronegativity1.91
Atomic Radius (pm)121
Ionization Energy (kJ/mol)737
Image of Nickel

By Materialscientist [ CC BY SA 3.0 ]

A piece of Ni about 3 cm in size.

Nickel was discovered in 1751 by A. F. Cronstedt in kupfernickel (niccolite), a copper-colored nickel arsenide mineral. Nickel is present in most meteorites. It is also found in trace amounts in plants and animals.

Cu

29

63.546

[Ar] 3d104s1

Copper

Year discoveredAncient
Standard statesolid
Melting point (K)1358
Boiling point (K)3200
Density (g/cm3)8.92
Key Isotopes63Cu
Oxidization States1, 2, 3, 4
Electronegativity1.9
Atomic Radius (pm)138
Ionization Energy (kJ/mol)746
Image of Copper

By Jonathan Zander [ CC BY SA 3.0 ]

Macro of native copper about 1 ½ inches (4 cm) in size.

Copper and some of its alloys have been used by humanity since the Bronze Age. One of the first metals known to humans, free copper was probably mined in the Tigris-Euphrates valley as long ago as the 5th cent. B.C. Cyprus, from which the metal's name originally comes, was the primary source of copper in the ancient world.

Zn

30

65.38

[Ar] 3d104s2

Zinc

Year discovered1746
Standard statesolid
Melting point (K)693
Boiling point (K)1180
Density (g/cm3)7.14
Key Isotopes64Zn
Oxidization States2
Electronegativity1.65
Atomic Radius (pm)131
Ionization Energy (kJ/mol)906
Image of Zinc

By Alchemist-hp [ CC BY NC ND 3.0 ]

Zinc, purity 99.995 %, left: a crystaline fragment of an ingot, right: sublimed-dendritic, and a 1 cm3 zinc cube for comparison.

The element was probably named by the alchemist Paracelsus after the German word Zinke. German chemist Andreas Sigismund Marggraf is normally given credit for discovering pure metallic zinc in 1746. Work by Luigi Galvani and Alessandro Volta uncovered the electrochemical properties of zinc by 1800

Ga

31

69.723

[Ar] 3d104s24p1

Gallium

Year discovered1875
Standard statesolid
Melting point (K)303
Boiling point (K)2477
Density (g/cm3)5.904
Key Isotopes69Ga
Oxidization States1, 2, 3
Electronegativity1.81
Atomic Radius (pm)126
Ionization Energy (kJ/mol)579
Image of Gallium

By Foobar [ CC BY SA 3.0 ]

Crystals of 99.999% gallium.

Gallium was an element whose existence was predicted by Mendeleev in 1871. He predicted that the then unknown element gallium should resemble aluminium in its properties. Gallium was discovered spectroscopically by Paul-Emile Lecoq de Boisbaudran in 1875, who in the same year obtained the free metal by electrolysis of a solution of the hydroxide

Ge

32

72.64

[Ar] 3d104s24p2

Germanium

Year discovered1886
Standard statesolid
Melting point (K)1211
Boiling point (K)3093
Density (g/cm3)5.323
Key Isotopes73Ge, 74Ge
Oxidization States-4, 1, 2, 3, 4
Electronegativity2.01
Atomic Radius (pm)122
Ionization Energy (kJ/mol)762
Image of Germanium

By Images of Elements [ CC BY 3.0 ]

Ultra pure chunk of polycrystalline germanium, 12 grams. Original size in cm: 2 x 3.

Germanium was an element whose existence was predicted by Mendeleev. He predicted that the then unknown element germanium should resemble silicon in its properties. His predictions for the properties of germanium are remarkably close to the reality. Germanium was discovered in a mineral called argyrodite by Clemens Alexander Winkler in 1886.

As

33

74.922

[Ar] 3d104s24p3

Arsenic

Year discoveredAncient
Standard statesolid
Melting point (K)1090
Boiling point (K)887
Density (g/cm3)5.727
Key Isotopes75As
Oxidization States-3, 2, 3, 5
Electronegativity2.18
Atomic Radius (pm)119
Ionization Energy (kJ/mol)947
Image of Arsenic

By Tomihahndorf [ CC BY SA 3.0 ]

Arsenic.

Arsenic compounds were mined by the early Chinese, Greek and Egyptian civilisations. No doubt they discovered its toxic properties early on. It is believed that Albertus Magnus obtained the element in 1250 A.D. who obtained it by heating soap together with orpiment (arsenic trisulphide, As2S3).

Se

34

78.96

[Ar] 3d104s24p4

Selenium

Year discovered1817
Standard statesolid
Melting point (K)494
Boiling point (K)958
Density (g/cm3)4.819
Key Isotopes80Se
Oxidization States-2, 2, 4, 6
Electronegativity2.55
Atomic Radius (pm)116
Ionization Energy (kJ/mol)941
Image of Selenium

By Images of Elements [ CC BY 3.0 ]

Black, amorphous selenium, 3 - 4 grams. Original size in cm: 2.

Selenium (Gr. Selen, moon) was discovered by Jöns Jacob Berzelius in 1817. He reported that tellurium was present in sulphuric acid from a Swedish factory, but in the following year decided that the impurity was not tellurium but another closely related element that he subsequently identified as selenium.

Br

35

79.904

[Ar] 3d104s24p5

Bromine

Year discovered1826
Standard stateliquid
Melting point (K)266
Boiling point (K)332
Density (g/cm3)3.12
Key Isotopes79Br
Oxidization States-1, 1, 3, 4, 5, 7
Electronegativity2.96
Atomic Radius (pm)114
Ionization Energy (kJ/mol)1140
Image of Bromine

By Images of Elements [ CC BY 3.0 ]

Bromine in a vial.

Bromine was discovered independently by two chemists, Carl Jacob Löwig and Antoine Jérôme Balard, in 1825 and 1826, respectively. Bromine was not prepared in quantity until 1860 but compounds of bromine were of some considerable importance well before it was recognised as an element. Long ago an excretion from a particular kind of mussel was used to make a purple dye called "Tyrian purple." It is now known that a key compound in this process is an organobromine compund.

Kr

36

83.798

[Ar] 3d104s24p6

Krypton

Year discovered1898
Standard stategas
Melting point (K)116
Boiling point (K)120
Density (g/cm3)0.00375
Key Isotopes84Kr
Oxidization States2
Electronegativity
Atomic Radius (pm)110
Ionization Energy (kJ/mol)1351
Image of Krypton

By Alchemist-hp [ CC BY NC ND 3.0 ]

Spectrum = gas discharge tube: the noble gas: krypton Kr. Used with 1,8kV, 18mA, 35kHz. ≈8" length.

Krypton was discovered in 1898 by Sir William Ramsay and his student Morris Travers in the residue left after liquid air had nearly boiled away. Krypton was left in the residue after boiling away water, oxygen, nitrogen, helium, and argon from the sample of air. Krypton is present in the air at about 1 ppm.

Rb

37

85.468

[Kr] 5s1

Rubidium

Year discovered1861
Standard statesolid
Melting point (K)312
Boiling point (K)961
Density (g/cm3)1.532
Key Isotopes85Rb, 87Rb
Oxidization States1
Electronegativity0.82
Atomic Radius (pm)211
Ionization Energy (kJ/mol)403
Image of Rubidium

By Dennis "S.K" [ CC BY 3.0 ]

Rubidium metal ampoule 99.99%+.

Rubidium was discovered with caesium in 1861 by Robert Bunsen and Gustav Kirchhoff; these were the first elements discovered by spectroscopic analysis. Although rubidium is much more abundant in the earth's crust than chromium, copper, lithium, nickel it did not become available commercially early 1960s

Sr

38

87.62

[Kr] 5s2

Strontium

Year discovered1790
Standard statesolid
Melting point (K)1050
Boiling point (K)1655
Density (g/cm3)2.63
Key Isotopes86Sr, 87Sr, 88Sr
Oxidization States2
Electronegativity0.95
Atomic Radius (pm)192
Ionization Energy (kJ/mol)550
Image of Strontium

By Alchemist-hp [ CC BY NC ND 3.0 ]

Strontium as synthetic crystals, sealed under argon in a glass ampoule, purity (99.95 %). Size of the image ca. 3cm * 4,7cm.

Adair Crawford in 1790 recognized a new mineral (strontianite) in samples of witherite (barium carbonate, BaCO3) from Scotland. It was some time before it was recognized that strontianite contained a new element. The element itself was not isolated for a number of years after this when strontium metal was isolated by Davy by electrolysis.

Y

39

88.906

[Kr] 4d15s2

Yttrium

Year discovered1794
Standard statesolid
Melting point (K)1799
Boiling point (K)3618
Density (g/cm3)4.472
Key Isotopes89Y
Oxidization States1, 2, 3
Electronegativity1.22
Atomic Radius (pm)162
Ionization Energy (kJ/mol)600
Image of Yttrium

By Images of Elements [ CC BY 3.0 ]

Ultra pure yttrium crystal. Original size in cm: 2 x 3.

Yttria (yttrium oxide, Y2O3), was discovered by Johann Gadolin in 1794 in a mineral called gadolinite from Ytterby, a town in Finland. Friedrich Wohler obtained the impure element in 1828 by reduction of the anhydrous chloride (YCl3) with potassium.

Zr

40

91.224

[Kr] 4d25s2

Zirconium

Year discovered1789
Standard statesolid
Melting point (K)2128
Boiling point (K)4682
Density (g/cm3)6.511
Key Isotopes90Zr, 92Zr, 94Zr
Oxidization States1, 2, 3, 4
Electronegativity1.33
Atomic Radius (pm)148
Ionization Energy (kJ/mol)640
Image of Zirconium

By Alchemist-hp [ CC BY NC ND 3.0 ]

Purest zirconium 99.97%, two samples of crystal bar showing different surface textures, made by crystal bar process, as well as a highly pure (99,95 % = 3N5) 1 cm3 zirconium cube for comparison. The metal piece-photo was taken on a white glass plate.

The name zircon probably originated from the arabic "zargun," which describes the colour of the gemstone now known as zircon. Zirconium was discovered by Martin Heinrich Klaproth at 1789 in Berlin, Germany. The minerals jargon, hyacinth, and jacinth also contain zircon and these have been known since biblical times and are mentioned in the bible.

Nb

41

92.906

[Kr] 4d45s1

Niobium

Year discovered1801
Standard statesolid
Melting point (K)2750
Boiling point (K)5017
Density (g/cm3)8.57
Key Isotopes93Nb
Oxidization States-1, 2, 3, 4, 5
Electronegativity1.6
Atomic Radius (pm)137
Ionization Energy (kJ/mol)652
Image of Niobium

By Images of Elements [ CC BY 3.0 ]

Niobium bead, slightly oxidized. Original size in cm: 0.6 x 0.6.

Niobium was discovered in 1801 by Charles Hatchett in an ore called columbite. He was not able to isolate the free element. There was then considerable confusion concerning the distinction between niobium and tantalum as they are so closely related. This confusion was resolved by Heinrich Rose, who named niobium.

Mo

42

95.96

[Kr] 4d55s1

Molybdenum

Year discovered1778
Standard statesolid
Melting point (K)2896
Boiling point (K)4912
Density (g/cm3)10.28
Key Isotopes95Mo, 96Mo, 98Mo
Oxidization States-2, -1, 1, 2, 3, 4, 5, 6
Electronegativity2.16
Atomic Radius (pm)145
Ionization Energy (kJ/mol)684
Image of Molybdenum

By Images of Elements [ CC BY 3.0 ]

Pure molybdenum crystal, about 20 grams. Original size in cm: 1.5 x 3.

Molybdenum was recognized as a distinct element in 1778 by Carl Wilhelm Scheele; its ore had earlier been confused with lead ore, hence its name. The element was isolated by P. J. Hjelm in 1782. Molybdenum do not occur uncombined in nature. It is widely but sparingly distributed throughout the world

Tc

43

98

[Kr] 4d55s2

Technetium

Year discovered1937
Standard statesolid
Melting point (K)2430
Boiling point (K)4538
Density (g/cm3)11.5
Key Isotopes
Oxidization States-3, -1, 1, 2, 3, 4, 5, 6, 7
Electronegativity1.9
Atomic Radius (pm)156
Ionization Energy (kJ/mol)702
Image of Technetium

By Images of Elements [ Public Domain ]

A piece of technetium.

Technetium was predicted on the basis of the periodic table by Mendeleev. The element was actually discovered by C. Perrier and Emilio Gino Segre in Italy in 1937. It was found in a sample of molybdenum bombarded by deuterons. Technetium was the first element to be produced artificially and all its isotopes are radioactive

Ru

44

101.07

[Kr] 4d75s1

Ruthenium

Year discovered1827
Standard statesolid
Melting point (K)2607
Boiling point (K)4423
Density (g/cm3)12.37
Key Isotopes101Ru, 102Ru, 104Ru
Oxidization States-2, 1, 2, 3, 4, 5, 6, 7, 8
Electronegativity2.2
Atomic Radius (pm)126
Ionization Energy (kJ/mol)710
Image of Ruthenium

By Alchemist-hp [ CC BY NC ND 3.0 ]

One half of a high-purity (99.99%), electron-beam-remelted ruthenium bar. Size ca. 40 × 15 × 10 mm, weight ca. 44 g.

Ruthenium was discovered in 1827 in an impure form by G. W. Osann in residues of crude platinum ores from the Ural Mts. of Russia. Pure ruthenium was first prepared by K. K. Klaus in 1845; he showed that Osann's sample contained at least one other metal.

Rh

45

102.906

[Kr] 4d85s1

Rhodium

Year discovered1803
Standard statesolid
Melting point (K)2237
Boiling point (K)3968
Density (g/cm3)12.45
Key Isotopes103Rh
Oxidization States-1, 1, 2, 3, 4, 5, 6
Electronegativity2.28
Atomic Radius (pm)135
Ionization Energy (kJ/mol)720
Image of Rhodium

By Images of Elements [ CC BY 3.0 ]

Pure rhodium bead, 1 gram. Original size in cm: 0.5.

William Hyde Wollaston discovered rhodium in 1803 in crude platinum ore from South America. He dissolved the ore in aqua regia, neutralised the acid with caustic soda, and precipitated the platinum & Palladium. The left material was a red material containing rhodium chloride salt from which rhodium metal was obtained by reduction with hydrogen gas.

Pd

46

106.42

[Kr] 4d10

Palladium

Year discovered1803
Standard statesolid
Melting point (K)1828
Boiling point (K)3236
Density (g/cm3)12.023
Key Isotopes106Pd
Oxidization States2, 4
Electronegativity2.2
Atomic Radius (pm)131
Ionization Energy (kJ/mol)804
Image of Palladium

By Images of Elements [ CC BY 3.0 ]

Palladium crystal, about 1 gram. Original size in cm: 0.5 x 1.

William Hyde Wollaston discovered palladium in 1803-4 in crude platinum ore from South America. He dissolved the ore in aqua regia, neutralised the acid with caustic soda, and precipitated the platinum .Palladium was then removed as palladium cyanide by treatment with mercuric cyanide. The metal was produced from this cyanide by heating.

Ag

47

107.868

[Kr] 4d105s1

Silver

Year discoveredAncient
Standard statesolid
Melting point (K)1235
Boiling point (K)2435
Density (g/cm3)10.49
Key Isotopes107Ag
Oxidization States1, 2, 3
Electronegativity1.93
Atomic Radius (pm)153
Ionization Energy (kJ/mol)731
Image of Silver

By Images of Elements [ CC BY 3.0 ]

Pieces of silver, 3 grams, the biggest piece is 1 cm long.

Silver has been known since ancient times. It is mentioned in Genesis. Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as early as 3000 B.C.

Cd

48

112.411

[Kr] 4d105s2

Cadmium

Year discovered1817
Standard statesolid
Melting point (K)594
Boiling point (K)1040
Density (g/cm3)8.65
Key Isotopes114Cd
Oxidization States2
Electronegativity1.69
Atomic Radius (pm)148
Ionization Energy (kJ/mol)868
Image of Cadmium

By Images of Elements [ CC BY 3.0 ]

Pure cadmium.

Cadmium was discovered by Friedrich Stromeyer in 1817 from an impurity in some samples of zinc carbonate. He noted that these particular samples changed colour on heating, which pure zinc carbonate does not. He was persistent to follow this observation through and he eventually isolated some cadmium metal by roasting and reduction of the sulphide.

In

49

114.818

[Kr] 4d105s25p1

Indium

Year discovered1863
Standard statesolid
Melting point (K)430
Boiling point (K)2345
Density (g/cm3)7.31
Key Isotopes115In
Oxidization States1, 2, 3
Electronegativity1.78
Atomic Radius (pm)144
Ionization Energy (kJ/mol)558
Image of Indium

By Dschwen [ CC BY SA 3.0 ]

Ductile indium wire with a thickness of about 3mm.

Indium was discovered by Ferdinand Reich and Theodore Richter, who later isolated the metal. It was found and spectroscopically identified as a minor component in zincores. Until 1924, a gram or so constituted the world's supply of this element in isolated form. In fact, it is probably about as abundant as silver.

Sn

50

118.71

[Kr] 4d105s25p2

Tin

Year discoveredAncient
Standard statesolid
Melting point (K)505
Boiling point (K)2875
Density (g/cm3)7.31
Key Isotopes120Sn
Oxidization States-4, 2, 4
Electronegativity1.96
Atomic Radius (pm)141
Ionization Energy (kJ/mol)709
Image of Tin

By Images of Elements [ CC BY 3.0 ]

Blob of tin. 3 x 3 cm.

Tin was known to the ancients and is mentioned in the Old Testament. Early metal workers found it too soft for most purposes but mixed with copper it gives the alloy bronze, of Bronze Age fame.

Sb

51

121.76

[Kr] 4d105s25p3

Antimony

Year discoveredAncient
Standard statesolid
Melting point (K)904
Boiling point (K)1860
Density (g/cm3)6.697
Key Isotopes121Sb
Oxidization States-3, 3, 5
Electronegativity2.05
Atomic Radius (pm)138
Ionization Energy (kJ/mol)834
Image of Antimony

By Images of Elements [ CC BY 3.0 ]

Antimony crystal, 2 grams, 1 cm.

Antimony was recognized in compounds by the ancients and was known as a metal at the beginning of the 17th century and possibly much earlier. It seems not to be clear who first recognised antimony as an element but the French chemist Nicolas Lémery conducted much of the earlier studies on antimony chemistry.

Te

52

127.6

[Kr] 4d105s25p4

Tellurium

Year discovered1782
Standard statesolid
Melting point (K)723
Boiling point (K)1261
Density (g/cm3)6.24
Key Isotopes130Te
Oxidization States-2, 2, 4, 5, 6
Electronegativity2.1
Atomic Radius (pm)135
Ionization Energy (kJ/mol)869
Image of Tellurium

By Images of Elements [ CC BY 3.0 ]

Metallic tellerium. 3.5cm diameter.

Tellurium was discovered in gold ores by Franz Joseph Muller von Reichenstein, the chief inspector of mines in Trannsylvania in 1782. However tellurium was named by M. Klaproth, who isolated it in 1798, after he continued Muller von Reichenstein's work.

I

53

126.904

[Kr] 4d105s25p5

Iodine

Year discovered1811
Standard statesolid
Melting point (K)387
Boiling point (K)457
Density (g/cm3)4.94
Key Isotopes127I
Oxidization States-1, 1, 3, 5, 7
Electronegativity2.66
Atomic Radius (pm)133
Ionization Energy (kJ/mol)1008
Image of Iodine

By IOCHEM Corporation

Iodine.

Iodine was discovered by Barnard Courtois in 1811. He isolated iodine from treating seaweed ash with sulphuric acid (H2SO4) while recovering sodium and potassium compounds.

Xe

54

131.293

[Kr] 4d105s25p6

Xenon

Year discovered1898
Standard stategas
Melting point (K)161
Boiling point (K)165
Density (g/cm3)0.0059
Key Isotopes132Xe
Oxidization States2, 4, 6, 8
Electronegativity
Atomic Radius (pm)130
Ionization Energy (kJ/mol)1170
Image of Xenon

By Alchemist-hp [ CC BY NC ND 3.0 ]

Spectrum = gas discharge tube: the noble gas: xenon Xe. Used with 1,8kV, 18mA, 35kHz. ≈8" length.

Xenon was discovered by Sir William Ramsay and Morris Travers in 1898 in the residue left after evaporating liquid air components. They had to work with huge volumes of air to produce just a little xenon since it turned out that xenon is only present to the extent of about 0.087 ppm in the atmosphere

Cs

55

132.905

[Xe] 6s1

Caesium

Year discovered1860
Standard statesolid
Melting point (K)302
Boiling point (K)944
Density (g/cm3)1.879
Key Isotopes133Cs
Oxidization States1
Electronegativity0.79
Atomic Radius (pm)225
Ionization Energy (kJ/mol)376
Image of Caesium

By Dennis "S.K" [ CC BY 3.0 ]

Caesium metal ampoule 99.99%+.

Caesium (cesium in USA) was discovered spectroscopically by Robert Wilhelm Bunsen in 1860 in samples of mineral water from Durkheim. Their identification was based upon two bright blue lines in the spectrum. The name caesium (from the Latin "caesius" - heavenly blue) was coined for its bright blue spectroscopic lines.

Ba

56

137.327

[Xe] 6s2

Barium

Year discovered1808
Standard statesolid
Melting point (K)1000
Boiling point (K)2143
Density (g/cm3)3.51
Key Isotopes138Ba
Oxidization States2
Electronegativity0.89
Atomic Radius (pm)198
Ionization Energy (kJ/mol)503
Image of Barium

By Matthias Zepper [ Public Domain ]

Pure barium in protective argon gas atmosphere.

Barium metal was first isolated in 1808 by Sir Humphry Davy by electrolysis. Its principal ore is barite (barium sulfate); it also occurs in the mineral witherite (barium carbonate). The pure metal is obtained by the electrolysis of fused barium salts or, industrially, by the reduction of barium oxide with aluminum

57-71

*

Lanthanides

Hf

72

178.49

[Xe] 4f145d26s2

Hafnium

Year discovered1923
Standard statesolid
Melting point (K)2506
Boiling point (K)4876
Density (g/cm3)13.31
Key Isotopes177Hf, 178Hf, 180Hf
Oxidization States2, 3, 4
Electronegativity1.3
Atomic Radius (pm)150
Ionization Energy (kJ/mol)659
Image of Hafnium

By Deglr6328 [ CC BY SA 3.0 ]

Hafnium turnings, >99.9% pure, used for evaporating onto glass as HfO2 to create multi-layer dielectric thin film optics in conjucntion with silica layers.

Hafnium was thought to be present in various zirconium minerals many years prior to its discovery, in 1923, which was credited to Dirk Coster and George Charles von Hevesey. It was finally identified in zircon from Norway, by means of X-ray spectroscopic analysis. It was named in honour of the city in which the discovery was made.

Ta

73

180.948

[Xe] 4f145d36s2

Tantalum

Year discovered1802
Standard statesolid
Melting point (K)3290
Boiling point (K)5731
Density (g/cm3)16.65
Key Isotopes180Ta, 181Ta
Oxidization States-1, 2, 3, 4, 5
Electronegativity1.5
Atomic Radius (pm)138
Ionization Energy (kJ/mol)761
Image of Tantalum

By Images of Elements [ CC BY 3.0 ]

Single piece of tantalum, each about 1 cm in size.

Niobium was discovered in by Anders Ekeberg, but many chemists thought niobium and tantalum were the same. Some felt that perhaps tantalum was an allotrope of niobium. Later, Rose, in 1844, and Marignac, in 1866, showed that niobic and tantalic acids were two different acids.The first relatively pure tantalum was produced by von Bolton in 1907.

W

74

183.84

[Xe] 4f145d46s2

Tungsten

Year discovered1783
Standard statesolid
Melting point (K)3695
Boiling point (K)5828
Density (g/cm3)19.25
Key Isotopes182W, 184W, 186W
Oxidization States-2, -1, 1, 2, 3, 4, 5, 6
Electronegativity2.36
Atomic Radius (pm)146
Ionization Energy (kJ/mol)770
Image of Tungsten

By Images of Elements [ CC BY 3.0 ]

Tungsten rod with oxidized surface, 80 grams. Original size in cm: 1.3 x 3.

Tungsten used to be known as wolfram (from wolframite, said to be named from wolf rahm or spumi lupi, because the ore interfered with the smelting of tin and was supposed to devour the tin). The de Elhuyar brothers found an acid in wolframite in 1783 that they succeeded in reducing to the elemental metal with charcoal.

Re

75

186.207

[Xe] 4f145d56s2

Rhenium

Year discovered1925
Standard statesolid
Melting point (K)3459
Boiling point (K)5869
Density (g/cm3)21.02
Key Isotopes187Re
Oxidization States-3, -1, 1, 2, 3, 4, 5, 6, 7
Electronegativity1.9
Atomic Radius (pm)159
Ionization Energy (kJ/mol)760
Image of Rhenium

By Images of Elements [ CC BY 3.0 ]

Small rhenium bead.

Discovery of rhenium is generally attributed to Walter Noddack, Ida Tacke-Noddack, and Otto Berg), who announced in 1925 they had detected the element in platinum ores and columbite.

Os

76

190.23

[Xe] 4f145d66s2

Osmium

Year discovered1803
Standard statesolid
Melting point (K)3306
Boiling point (K)5285
Density (g/cm3)22.61
Key Isotopes192Os
Oxidization States-2, -1, 1, 2, 3, 4, 5, 6, 7, 8
Electronegativity2.2
Atomic Radius (pm)128
Ionization Energy (kJ/mol)840
Image of Osmium

By [ CC BY 3.0 ]

Cluster of osmium crystals grown by chemical vapor transport.

Osmium was discovered in 1803 by Smithson Tennant in the dark coloured residue left when crude platinum is dissolved by aqua regia (a mixture of hydrochloric and nitric acid). This dark residue contains both osmium (named after osme meaning odour) and iridium.

Ir

77

192.217

[Xe] 4f145d76s2

Iridium

Year discovered1803
Standard statesolid
Melting point (K)2739
Boiling point (K)4701
Density (g/cm3)22.65
Key Isotopes193Ir
Oxidization States-3, -1, 1, 2, 3, 4, 5, 6
Electronegativity2.2
Atomic Radius (pm)137
Ionization Energy (kJ/mol)880
Image of Iridium

By Images of Elements [ CC BY 3.0 ]

Pieces of pure iridium.

Osmium was discovered in 1803 by Smithson Tennant in the dark coloured residue left when crude platinum is dissolved by aqua regia (a mixture of hydrochloric and nitric acid). This dark residue contains both osmium and iridium (named after the Latin word iris meaning rainbow because of the colourful nature of iridium compounds).

Pt

78

195.084

[Xe] 4f145d96s1

Platinum

Year discoveredAncient
Standard statesolid
Melting point (K)2041
Boiling point (K)4098
Density (g/cm3)21.09
Key Isotopes195Pt
Oxidization States2, 4, 5, 6
Electronegativity2.28
Atomic Radius (pm)128
Ionization Energy (kJ/mol)870
Image of Platinum

By Images of Elements [ CC BY 3.0 ]

Two platinum crystals, each 1 cm big, together about 1 gram.

The metal was used by pre-Columbian Indians but platinum was "rediscovered" in South America by Ulloa in 1735 and by Wood in 1741. In 1822 plenty of platinum was discovered in the Ural Mountains in Russia.

Au

79

196.967

[Xe] 4f145d106s1

Gold

Year discoveredAncient
Standard statesolid
Melting point (K)1337
Boiling point (K)3129
Density (g/cm3)19.3
Key Isotopes197Au
Oxidization States-1, 1, 2, 3, 5
Electronegativity2.54
Atomic Radius (pm)144
Ionization Energy (kJ/mol)890
Image of Gold

By Images of Elements [ CC BY 3.0 ]

5g gold bar.

Gold has been known from prehistoric times and was possibly the first metal used by humans. It was valued for ornaments and magical efficacy was attributed to it. In the Middle Ages alchemists sought to transmute baser metals into gold. The quest for gold stimulated European explorations and conquests, and its discovery has led to many a gold rush.

Hg

80

200.59

[Xe] 4f145d106s2

Mercury

Year discoveredAncient
Standard stateliquid
Melting point (K)234
Boiling point (K)630
Density (g/cm3)13.534
Key Isotopes202Hg
Oxidization States1, 2, 4
Electronegativity2
Atomic Radius (pm)149
Ionization Energy (kJ/mol)1007
Image of Mercury

By Britannica Online for Kids. Web

Mercury.

Mercury was known to ancient Chinese and Hindus before 2000 BC and was found in tubes in Egyptian tombs dated from 1500 BC It was used to forma amalgams of other metals around 500 BC. The Greeks used mercury in ointments and the Romans used it, unfortunately for those using it, in cosmetics.

Tl

81

204.383

[Xe] 4f145d106s26p1

Thallium

Year discovered1861
Standard statesolid
Melting point (K)577
Boiling point (K)1746
Density (g/cm3)11.85
Key Isotopes205Tl
Oxidization States1, 3
Electronegativity2.04
Atomic Radius (pm)148
Ionization Energy (kJ/mol)589
Image of Thallium

By W. Oelen [ CC BY SA 3.0 ]

Pieces of very pure thallium in glass ampoule under argon.

Thallium was discovered spectroscopically in 1861 by William Crookes. The element was named after the green spectral line, which identified the element (Greek "thallos", green twig). They had been expecting to isolate tellurium after removing selenium from the byproducts from a commercial sulphuric acid factory but instead found the new element thallium.

Pb

82

207.2

[Xe] 4f145d106s26p2

Lead

Year discoveredAncient
Standard statesolid
Melting point (K)601
Boiling point (K)2022
Density (g/cm3)11.34
Key Isotopes208Pb
Oxidization States-4, 2, 4
Electronegativity2.33
Atomic Radius (pm)147
Ionization Energy (kJ/mol)716
Image of Lead

By Images of Elements [ CC BY 3.0 ]

Two pieces of lead, 11 grams, 1 x 1.5 cm each.

Lead has been known for ages and is mentioned in Exodus. Alchemists believed lead to be the oldest metal and associated it with the planet Saturn. They spent a lot of time trying to "transmute" lead into gold.

Bi

83

208.98

[Xe] 4f145d106s26p3

Bismuth

Year discoveredAncient
Standard statesolid
Melting point (K)544
Boiling point (K)1837
Density (g/cm3)9.78
Key Isotopes209Bi
Oxidization States-3, 3, 5
Electronegativity2.02
Atomic Radius (pm)146
Ionization Energy (kJ/mol)703
Image of Bismuth

By Dschwen [ CC BY SA 3.0 ]

Bismuth crystal.

In early times bismuth was confused with tin and lead. So although bismuth had been discussed many times before, Claude Geoffroy the Younger showed it to be distinct from lead in 1753.

Po

84

209

[Xe] 4f145d106s26p4

Polonium

Year discovered1898
Standard statesolid
Melting point (K)527
Boiling point (K)1235
Density (g/cm3)9.196
Key Isotopes209Po, 210Po
Oxidization States-2, 2, 4, 6
Electronegativity2
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)812

Polonium was the first element discovered by Marie Sklodowska Curie in 1898, while seeking the cause of radioactivity of pitchblende from Joachimsthal, Bohemia. It required several tonnes of pitchblende to produce very small amounts of polonium.

At

85

210

[Xe] 4f145d106s26p5

Astatine

Year discovered1940
Standard statesolid
Melting point (K)575
Boiling point (K)623
Density (g/cm3)Unknown
Key Isotopes210At
Oxidization States-1, 1, 3, 5
Electronegativity2.2
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)920

Astatine was synthesized in 1940 by Dale Corson, Kenneth Ross MacKenzie and Emilio Segrèand others at the University of California, USA, by bombarding bismuth (209Bi) with alpha particles.

Rn

86

222

[Xe] 4f145d106s26p6

Radon

Year discovered1900
Standard stategas
Melting point (K)202
Boiling point (K)211
Density (g/cm3)0.00973
Key Isotopes211Rn, 220Rn, 222Rn
Oxidization States2
Electronegativity
Atomic Radius (pm)145
Ionization Energy (kJ/mol)1037

Radon was discovered in 1900 by Friedrich Ernst Dorn, who called it niton. It is essentially inert. It has been called radon since 1923, before which it was called niton.

Fr

87

223

[Rn] 7s1

Francium

Year discovered1939
Standard statesolid
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes223Fr
Oxidization States1
Electronegativity0.7
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)380

Francium was discovered in 1939 by Marguerite Perey of the Curie Institute in Paris, (France) but its existence was predicted by Mendeleev during the 1870's. Since its properties should track those of caesium rather closely, he called it eka-caesium.

Ra

88

226

[Rn] 7s2

Radium

Year discovered1898
Standard statesolid
Melting point (K)973
Boiling point (K)2010
Density (g/cm3)5
Key Isotopes226Ra
Oxidization States2
Electronegativity0.9
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)509

Radium was discovered in 1898 by Marie and Pierre Curie in pitchblende (or uraninite) from North Bohemia. The element was isolated in 1911 by Mme. Curie and Debierne by the electrolysis of a solution of pure radium chloride, employing a mercury cathode. On distillation in an atmosphere of hydrogen this amalgam yielded the pure metal.

89-103

**

Actinides

Rf

104

267

[Rn] 5f146d27s2

Rutherfordium

Year discovered1969
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes265Rf
Oxidization States4
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In 1969 an American group at Berkeley (California) in the USA reported isotopes of Element 104. Their experiments involved reaction high energy collisions between 249Cf and 12C. The group also indicated that they were unable to reproduce the earlier Russian synthesis from1964. The American group proposed for the new element the name Rutherfordiu

Db

105

268

[Rn] 5f146d37s2

Dubnium

Year discovered1967
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes268Db
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In 1967, Flerov reported element 105 after experiments at the Joint Research Institute in Russia involving reactions between 243Am ions with 22Ne ions. In 1970, Ghiorso and others announced their synthesis of dubnium at Berkeley (California) in the USA. This method involved the collsion of 249Cf ions with 15N ions.

Sg

106

271

[Rn] 5f146d47s2

Seaborgium

Year discovered1974
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes271Sg
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Transuranium elements such as seaborgium can be created artificially in particle accelerators. Isotopes of seaborgium have short half-lives of less than a second. The first report of element 106 came in 1974 from the Soviet Joint Institute for Nuclear Research and these were followed later by others from Berkeley in California, USA.

Bh

107

272

[Rn] 5f146d57s2

Bohrium

Year discovered1976
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes272Bh
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Scientists from the USSR reported their production of an isotope of bohrium in 1976 and this work was substantiated by German workers later.

Hs

108

270

[Rn] 5f146d67s2

Hassium

Year discovered1984
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes270Hs
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Hassium was discovered by Peter Armbruster, Gottfried Münzenber and their co-workers. at 1984 in Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. The origin of the name is the Latin word "Hassias" meaning "Hess", the German state.

Mt

109

276

[Rn] 5f146d77s2

Meitnerium

Year discovered1982
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes276Mt
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In August 1982 the first atom of the element meitnerium with atomic number 109 was detected at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. The isotope of element 109 which was discovered has an atomic mass number of 266 (that is, 266 times heavier than hydrogen)

Ds

110

281

[Rn] 5f146d97s1

Darmstadtium

Year discovered1994
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes281Ds
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In 1994 the first atom of element 110, darmstadtium, was detected at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. The isotope discovered has an atomic number of 269 (that is, 269 times heavier than hydrogen).

Rg

111

280

[Rn] 5f146d107s1

Roentgenium

Year discovered1994
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes280Rg
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Element 111, roentgenium, was discovered towards the end of 1994 at the GSI in Darmstadt, Germany. Three atoms of an isotope 272Uuu were produced in reactions between 209Bi targets and 64Ni projectiles. To achieve this, the nickel atoms were accelerated to high energies by the heavy ion accelerator UNILAC at GSI and directed onto a lead target.

Cn

112

285

[Rn] 5f146d107s2

Copernicium

Year discovered1996
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes285Cn
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Element 112 was discovered on 9th February 1996 at 22:37 at the GSI in Darmstadt, Germany. The identified isotope currently is the heaviest atom ever produced by man and has an atomic mass of 277, that is, 277 times heavier than hydrogen.

Nh

113

284

[Rn] 5f146d107s27p1

Nihonium

Year discovered2003
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes284Nh
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In experiments conducted at the JINR U400 cyclotron with the Dubna gas-filled separator between July 14 and Aug. 10, 2003, atomic decay patterns were observed said to confirm the existence of element 115 and element 113. In these decay chains, element 113 is produced via the ?-decay of element 115.

* Nihonium (Nh) is a provisional name.

Fl

114

289

[Rn] 5f146d107s27p2

Flerovium

Year discovered1998
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes289Fl
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In experiments conducted at the JINR U400 cyclotron with the Dubna gas-filled separator between July 14 and Aug. 10, 2003, atomic decay patterns were observed said to confirm the existence of element 115 and element 113. In these decay chains, element 113 is produced via the ?-decay of element 115.

Mc

115

288

[Rn] 5f146d107s27p3

Moscovium

Year discovered2003
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes288Mc
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

In experiments conducted at the JINR U400 cyclotron with the Dubna gas-filled separator between July 14 and Aug. 10, 2003, atomic decay patterns were observed said to confirm the existence of element 115 and element 113. In these decay chains, element 113 is produced via the ?-decay of element 115.

* Moscovium (Mc) is a provisional name.

Lv

116

293

[Rn] 5f146d107s27p4

Livermorium

Year discovered2000
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes293Lv
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Results published on the 6th December 2000 concerning recent experiments at Dubna in Russia describe the decay of the isotope 292Uuh (produced in the reaction of 248Cm with 48Ca) to 292Uuq. This decayed 47 milliseconds later as follows to a previously identified isotope of elements 114, Uuq.

Ts

117

294

[Rn] 5f146d107s27p5

Tennessine

Year discovered2010
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes292Ts
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Claims for the formation of element 117 (ununseptium, Uus) were first published in April 2010.

* Tennessine (Ts) is a provisional name.

Og

118

294

[Rn] 5f146d107s27p6

Oganesson

Year discovered2002
Standard stateUnknown
Melting point (K)Unknown
Boiling point (K)N/A
Density (g/cm3)Unknown
Key Isotopes294Og
Oxidization StatesUnknown
Electronegativity
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Experiments conducted at Dubna in Russia at the Flerov Laboratory of Nuclear Reactions (by workers from the Joint Institute for Nuclear Research in Russia and the Lawrence Livermore National Laboratory in the USA) indicate that element 118 (ununoctium, Uuo) was produced. Not too much though, one atom in the spring of 2002 and two more in 2005.

* Oganesson (Og) is a provisional name.

La

57

138.905

[Xe] 5d16s2

Lanthanum

Year discovered1839
Standard statesolid
Melting point (K)1193
Boiling point (K)3737
Density (g/cm3)6.146
Key Isotopes139La
Oxidization States2, 3
Electronegativity1.1
Atomic Radius (pm)169
Ionization Energy (kJ/mol)538
Image of Lanthanum

By Images of Elements [ CC BY 3.0 ]

1.5 grams pure lanthanum. Original size in cm: 1 x 1.

Carl Gustav Mosander recognized the element lanthanum in impure cerium nitrate in 1839. His extraction resulted in the oxide lanthana (La2O3). A number of other lanthanides (rare-earths) were later discovered by identification of the impurities in yttrium and cerium compounds.

Ce

58

140.116

[Xe] 4f15d16s2

Cerium

Year discovered1803
Standard statesolid
Melting point (K)1071
Boiling point (K)3633
Density (g/cm3)6.689
Key Isotopes
Oxidization States2, 3, 4
Electronegativity1.12
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)534
Image of Cerium

By Images of Elements [ CC BY 3.0 ]

Cerium under argon, 1.5 grams. Original size in cm: 1 x 1.

Cerium was discovered in 1803 by Jöns Jacob Berzeliusf and Wilhelm Hisinger and independently by Martin Klaproth. It was isolated from a mineral from an iron mine at Bastn°s

Pr

59

140.908

[Xe] 4f36s2

Praseodymium

Year discovered1885
Standard statesolid
Melting point (K)1204
Boiling point (K)3563
Density (g/cm3)6.64
Key Isotopes141Pr
Oxidization States2, 3, 4
Electronegativity1.13
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)527
Image of Praseodymium

By Images of Elements [ CC BY 3.0 ]

Praseodymium pieces under argon, 1.5 grams. Original size in cm: 0.5 - 1.

In 1885, Carl Auer von Welsbach separated an "earth" called didymia obtained from the mineral samarskite into two earths, praseodymia and neodymia, which gave salts of different colours. The separation required the repeated fractionation of ammonium didymium nitrate.

Nd

60

144.242

[Xe] 4f46s2

Neodymium

Year discovered1885
Standard statesolid
Melting point (K)1294
Boiling point (K)3373
Density (g/cm3)7.01
Key Isotopes142Nd
Oxidization States2, 3
Electronegativity1.14
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)533
Image of Neodymium

By Images of Elements [ CC BY 3.0 ]

Neodymium under argon, 5 grams. Original length of the large piece in cm: 1.

In 1885 von Welsbach separated didymium, an extract of cerite, into two new elemental components, neodymia and praseodymia, by repeated fractionation of ammonium didymium nitrate. While the free metal is a component of misch metal, (a pyrophoric alloy for lighter flints), the element was not isolated in relatively pure form until 1925.

Pm

61

145

[Xe] 4f56s2

Promethium

Year discovered1947
Standard statesolid
Melting point (K)1373
Boiling point (K)3273
Density (g/cm3)7.264
Key Isotopes145Pm, 147Pm
Oxidization States3
Electronegativity1.13
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)540

Early claims to the discovery of promethium date back to 1924 but these appear have been substantiated. A group at Ohio State University claimed element 61 in experiments involving its synthesis in a cyclotron. Marinsky, Glendenin, and Coryell's at Tennessee made the first chemical identification of promethium by use of ion-exchange chromatography

Sm

62

150.36

[Xe] 4f66s2

Samarium

Year discovered1853
Standard statesolid
Melting point (K)1345
Boiling point (K)2076
Density (g/cm3)7.353
Key Isotopes152Sm
Oxidization States2, 3
Electronegativity1.17
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)545
Image of Samarium

By Images of Elements [ CC BY 3.0 ]

Sublimated samarium, 2 grams. Original size in cm: 0.8 x 1.5.

Samarium was discovered spectroscopically by its sharp absorption lines in 1853 by Jean Charles Galissard de Marignac in an "earth" called didymia. The element was isolated in 1879 by Lecoq de Boisbaudran from the mineral samarskite, named in honour of a Russian mine official, Colonel Samarski, and which therefore gave samarium its name.

Eu

63

151.964

[Xe] 4f76s2

Europium

Year discovered1901
Standard statesolid
Melting point (K)1095
Boiling point (K)1800
Density (g/cm3)5.244
Key Isotopes153Eu
Oxidization States2, 3
Electronegativity1.2
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)547
Image of Europium

By Images of Elements [ CC BY 3.0 ]

Weakly oxidized europium, hence slightly yellowish. 1.5 grams, large piece 0.6 x 1.6 cm.

The discovery of europium is generally credited to Eugène-Antole Demarçay, who separated the earth in reasonably pure form in 1901 from a material containing largely samarium. Pure europium metal was not isolated until much more recently.

Gd

64

157.25

[Xe] 4f75d16s2

Gadolinium

Year discovered1880
Standard statesolid
Melting point (K)1586
Boiling point (K)3523
Density (g/cm3)7.901
Key Isotopes158Gd
Oxidization States1, 2, 3
Electronegativity1.2
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)593
Image of Gadolinium

By Images of Elements [ CC BY 3.0 ]

Ultra pure amorphous gadolinium, 12 grams. Original size in cm: 1.5 x 2.

Spectroscopic lines due to gadolinium were observed by Jean Charles Galissard de Marignac in 1880 in samples of didymia and gadolinite. Gadolinia, the oxide of gadolinium, was separated by Paul-Emile Loq de Biosbaudran in 1886. The element was named for the mineral gadolinite from which this rare earth was originally obtained.

Tb

65

158.925

[Xe] 4f96s2

Terbium

Year discovered1843
Standard statesolid
Melting point (K)1629
Boiling point (K)3503
Density (g/cm3)8.219
Key Isotopes159Tb
Oxidization States1, 3, 4
Electronegativity1.2
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)566
Image of Terbium

By Tomihahndorf [ CC BY SA 3.0 ]

Chunk of terbium.

Terbium was discovered by Gustav Mosander in 1843. He detected it is as an impurity in yttria which is yttrium oxide, Y2O3.

Dy

66

162.5

[Xe] 4f106s2

Dysprosium

Year discovered1886
Standard statesolid
Melting point (K)1685
Boiling point (K)2840
Density (g/cm3)8.551
Key Isotopes164Dy
Oxidization States2, 3
Electronegativity1.22
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)573
Image of Dysprosium

By Images of Elements [ CC BY 3.0 ]

Dysprosium dendrites. Original size in cm: 2 x 2.

A little dysprosium oxide was identified in 1886 by Paul-Emile Lecoq de Boisbaudran as an impurity in erbia (erbium oxide), but the element itself not isolated at that time. Neither the oxide nor the metal was available in relatively pure form following the development of ion-exchange separation and metallographic reduction techniques.

Ho

67

164.93

[Xe] 4f116s2

Holmium

Year discovered1878
Standard statesolid
Melting point (K)1747
Boiling point (K)2973
Density (g/cm3)8.795
Key Isotopes165Ho
Oxidization States3
Electronegativity1.23
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)581
Image of Holmium

By Images of Elements [ CC BY 3.0 ]

Holmium, 17 grams. Original size in cm: 1.5 x 2.5.

Per Theodor Cleve of Sweden discovered holmium while working on erbia earth (erbium oxide). Holmium oxide (holmia) was present as an impurity in the erbia. The element is named after Cleve's native city. Pure holmia, the yellow oxide, was prepared at Homberg in 1911.

Er

68

167.259

[Xe] 4f126s2

Erbium

Year discovered1842
Standard statesolid
Melting point (K)1770
Boiling point (K)3141
Density (g/cm3)9.066
Key Isotopes166Er
Oxidization States3
Electronegativity1.24
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)589
Image of Erbium

By Tomihahndorf [ CC BY SA 3.0 ]

Chunk of erbium.

In 1842 Gustav Mosander separated "yttria", found in the mineral gadolinite, into three fractions which he called yttria, erbia, and terbia. The names erbia and terbia became confused in this early period. After 1860, Mosander's terbia was known as erbia, and after 1877, the earlier known erbia became terbia.

Tm

69

168.934

[Xe] 4f136s2

Thulium

Year discovered1879
Standard statesolid
Melting point (K)1818
Boiling point (K)2223
Density (g/cm3)9.321
Key Isotopes169Tm
Oxidization States2, 3
Electronegativity1.25
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)597
Image of Thulium

By Alchemist-hp [ CC BY NC ND 3.0 ]

Thulium, sublimed-dendritic, high purity 99.99 % Tm/TREM.

Per Theodor Cleve of Sweden discovered holmium in 1879 while working on erbia earth (erbium oxide). Thulium oxide (holmia) was present as an impurity in the erbia. The element is named after Thule, the ancient name for Scandinavia.

Yb

70

173.054

[Xe] 4f146s2

Ytterbium

Year discovered1878
Standard statesolid
Melting point (K)1092
Boiling point (K)1469
Density (g/cm3)6.57
Key Isotopes172Yb, 173Yb, 174Yb
Oxidization States2, 3
Electronegativity1.1
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)603
Image of Ytterbium

By Images of Elements [ CC BY 3.0 ]

Ytterbium, 0.5 x 1 cm.

In 1878 Jean Charles Galissard de Marignac discovered a component, which he called ytterbia, in the earth then known as erbia. In 1907, Urbain separated ytterbia into two components, which he called neoytterbia and lutecia. The elements in these earths are now known as ytterbium and lutetium, respectively.

Lu

71

174.967

[Xe] 4f145d16s2

Lutetium

Year discovered1907
Standard statesolid
Melting point (K)1936
Boiling point (K)3675
Density (g/cm3)9.841
Key Isotopes175Lu
Oxidization States3
Electronegativity1.27
Atomic Radius (pm)160
Ionization Energy (kJ/mol)524
Image of Lutetium

By Images of Elements [ CC BY 3.0 ]

Piece of lutetium, 3 grams. Original size in cm: 1 x 1.

In 1907, Georges Urbain described a process by which Marignac's ytterbium (1879) could be separated into the two elements, ytterbium (neoytterbium) and lutetium. These elements were identical with "aldebaranium" and "cassiopeium", independently discovered by von Welsbach at about the same time.

Ac

89

227

[Rn] 6d17s2

Actinium

Year discovered1899
Standard statesolid
Melting point (K)1323
Boiling point (K)3473
Density (g/cm3)10.07
Key Isotopes227Ac
Oxidization States3
Electronegativity1.1
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)499
Image of Actinium

By US Department of Energy

Actinium-225 samples held in two v-vials.

Actinium was discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902, both of whom obtained it while working on separation techniques for rare earth oxides.

Th

90

232.038

[Rn] 6d27s2

Thorium

Year discovered1828
Standard statesolid
Melting point (K)2023
Boiling point (K)5093
Density (g/cm3)11.724
Key Isotopes230Th, 232Th
Oxidization States2, 3, 4
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)587

Pa

91

231.036

[Rn] 5f26d17s2

Protactinium

Year discovered1913
Standard statesolid
Melting point (K)1845
Boiling point (K)4273
Density (g/cm3)15.37
Key Isotopes231Pa
Oxidization States3, 4, 5
Electronegativity1.5
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)568

Protactinium is found in pitchblende and ores from DR Congo and is one of the rarest and most expensive naturally occurring elements. Protactinium was identified by Kasimir Fajans and Otto Hahn in 1913 who named the new element brevium.

U

92

238.029

[Rn] 5f36d17s2

Uranium

Year discovered1789
Standard statesolid
Melting point (K)1408
Boiling point (K)4200
Density (g/cm3)19.05
Key Isotopes234U, 235U, 238U
Oxidization States3, 4, 5, 6
Electronegativity1.38
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)598
Image of Uranium

By [ Public Domain ]

Depleted uranium 238.

Martin Heinrich Klaproth recognized an unknown element in pitchblende and attempted to isolate the metal in 1789. He named the element for the planet uranus which had just been discovered. The radioactive nature of uranium was not appreciated for another 55 years when in 1896 Henri Becquerel detected its radioactivity.

Np

93

237

[Rn] 5f46d17s2

Neptunium

Year discovered1940
Standard statesolid
Melting point (K)917
Boiling point (K)4273
Density (g/cm3)20.45
Key Isotopes237Np
Oxidization States3, 4, 5, 6, 7
Electronegativity1.36
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)605
Image of Neptunium

By [ Public Domain ]

Neptunium 237 sphere (6 kg).

Neptunium was the first synthetic transuranium element of the actinide series. It was discovered by Edwin McMillan and Philip Abelson in 1940 at Berkeley, California, USA, who bombarded uranium with neutrons produced from a cyclotron. It was the first synthetic transuranium (elements after uranium) element discovered.

Pu

94

244

[Rn] 5f67s2

Plutonium

Year discovered1940
Standard statesolid
Melting point (K)913
Boiling point (K)3503
Density (g/cm3)19.816
Key Isotopes238Pu, 239Pu, 240Pu
Oxidization States3, 4, 5, 6, 7
Electronegativity1.28
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)585
Image of Plutonium

By U.S. Department of Energy, [ Public Domain ]

Plutonium, a silvery, very heavy and hard metal.

Plutonium was synthesized by Seaborg, McMillan, Kennedy and Wahl in 1940 by deuteron bombardment of uranium in a cyclotron (a device used to accelerate atomic particles) at Berkeley, USA. Plutonium was the second transuranium element of the actinide series to be discovered.

Am

95

243

[Rn] 5f77s2

Americium

Year discovered1944
Standard statesolid
Melting point (K)1449
Boiling point (K)2284
Density (g/cm3)Unknown
Key Isotopes241Am, 243Am
Oxidization States2, 3, 4, 5, 6
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)578
Image of Americium

By Bionerd [ CC BY 3.0 ]

A small disc of Am-241 under the microscope.

Americium was was identified by Seaborg and others in 1944 as the result of successive neutron capture reactions by plutonium isotopes in a nuclear reactor.

Cm

96

247

[Rn] 5f76d17s2

Curium

Year discovered1944
Standard statesolid
Melting point (K)1618
Boiling point (K)3383
Density (g/cm3)13.51
Key Isotopes243Cm, 248Cm
Oxidization States3, 4
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)581

Curium was identified by Seaborg and others in 1944 as a result of helium ion bombardment of the plutonium isotope 239Pu. Three years later visible amounts of the hydroxide were isolated by Werner and Perlman. In 1951, the same workers prepared curium in its elemental form for the first time.

Bk

97

247

[Rn] 5f97s2

Berkelium

Year discovered1949
Standard statesolid
Melting point (K)1323
Boiling point (K)Unknown
Density (g/cm3)14.78
Key Isotopes247Bk, 249Bk
Oxidization States3, 4
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)601
Image of Berkelium

By ORNL, Department of Energy [ Public Domain ]

It took 250 days to make enough berkelium, shown here (in dissolved state), to synthesize element 117.

Berkelium was discovered in December 1949 at Berkeley, Californi, USA, by Ghiorso and others by cyclotron bombardment of milligram amounts of americium with helium ions. Perhaps the first visible amounts of a pure berkelium compound, berkelium chloride, was produced in 1962. It weighed just 3 billionth of a gram.

Cf

98

251

[Rn] 5f107s2

Californium

Year discovered1950
Standard statesolid
Melting point (K)1173
Boiling point (K)Unknown
Density (g/cm3)15.1
Key Isotopes249Cf, 252Cf
Oxidization States2, 3, 4
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)608
Image of Californium

By United States Department of Energy [ Public Domain ]

A very small disc of californium.

Californium was produced by Ghiorso and others at the University of California, Berkeley, USA in 1950 who bombarded 242Cm with helium ions.

Es

99

252

[Rn] 5f117s2

Einsteinium

Year discovered1952
Standard statesolid
Melting point (K)1133
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes252Es
Oxidization States2, 3
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)619
Image of Einsteinium

By US Department of Energy. [ Public Domain ]

Quartz vial (9 mm diameter) containing ~300 micrograms of Es-253 solid. The illumination produced is a result of the intense radiation from Es-253, which alpha decays (6.6 MeV, 1000 watts/g) with a half-life of 20.5 days.

Einsteinium was identified by Ghiorso and others (Berkeley, California, USA) in 1952 in radioactive debris from the first large thermonuclear bomb explosion, which took place in the Pacific in November 1952. In 1961, a sufficient amount of einsteinium was produced to permit separation of a macroscopic amount of 253Es.

Fm

100

257

[Rn] 5f127s2

Fermium

Year discovered1952
Standard stateUnknown
Melting point (K)1800
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes257Fm
Oxidization States2, 3
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)627

Fermium was identified by Ghiorso and coworkers (Berkeley, California, USA) in 1952 in the radioactive debris from a thermonuclear explosion in the Pacific. Somewhat remarkably, the fermium isotope discovered was made through the combination of 238U with 17 neutrons. Today, many isotopes are known spanning the mass range 243-258.

Md

101

258

[Rn] 5f137s2

Mendelevium

Year discovered1955
Standard stateUnknown
Melting point (K)1100
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes258Md, 260Md
Oxidization States2, 3
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)635

Mendelevium, the ninth transuranium element of the actinide series to be discovered, was first identified by Seaborg and others in 1955 as a product of the bombardment of the einsteinium isotope 253Es with helium ions. The isotope produced was 256Md, which has a half-life of about 11/4 hours.

No

102

259

[Rn] 5f147s2

Nobelium

Year discovered1957
Standard stateUnknown
Melting point (K)1100
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes259No
Oxidization States2, 3
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)642

A team working in Stockholm reported in 1957 an isotope whose atomic number is 102. They made this isotope by bombardment of 244Cm with 13C ions. They named the element nobelium after Alfred Nobel.

Lr

103

262

[Rn] 5f147s27p1

Lawrencium

Year discovered1961
Standard stateUnknown
Melting point (K)1900
Boiling point (K)Unknown
Density (g/cm3)Unknown
Key Isotopes262Lr
Oxidization States3
Electronegativity1.3
Atomic Radius (pm)Unknown
Ionization Energy (kJ/mol)Unknown

Element 103, lawrencium, was discovered in 1961 by Ghiorso and others in Berkeley, California, USA, who bombarded a californium target with boron ions. They obtained perhaps two micrograms. Several lawrencium isotopes including those with masses 253, 254, 255, 256, 257, 258, 259, and 260 are known now.