PHYSCHEM - THE PERIODIC TABLE

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	1 1.008 37 2.1 1312 0.08988 -252.7 -259.14	1s	2s	2p
		1

Helium (He): First isolated in 1895 by Ramsay. The name is derived from the greek helios, meaning "sun". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	2 4.003 93 0.0 1372 0.1785 -268.9 -272	1s	2s	2p
		2

Lithium (Li): Discovered by Aefvedson in 1817. The name is derived from the greek lithos , meaning "stone". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	3 6.939 152 1.0 520 0.534 1336 180.54	1s	2s	2p
		2	1

Beryllium (Be): Discovered as the oxide by Vauquelin in 1798. First isolated independently by Wohler and Bussy in 1828. The name is derived from its mineral beryl. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	4 9.102 111 1.5 899 1.8477 ±2500 1287	1s	2s	2p
		2	2

Boron (B): Discovered in 1808 by Sir Humphrey Davy, Gay-Lussac and Thenard. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	5 10.811 79 1.5 800 2.45 2550 2200	1s	2s	2p
		2	2	1

Carbon (C): Occurs naturally and has been known since prehistoric times. The name is derived from the latin carbo, meaning "charcoal". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	6 12.01 77 2.5 1086	1s	2s	2p
		2	2	2

Nitrogen (N): Discovered by Daniel Rutherford in 1772. The name is derived from the latin nitrum (soda) and means "soda forming". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	7 14.007 74 3.0 1403 1.2506 -195.79 -210.01	1s	2s	2p
		2	2	3

Oxygen (F): Discovered by Priestley, and independently by Scheele. The name is derived from the greek words oxys (acid) and genes (forming). (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	8 16.000 74 3.5 1313 1.429 -182.96 -218.4	1s	2s	2p
		2	2	4

Fluorine (F): First isolated by Moissan in 1866. The name is derived from the latin fluere (to flow). (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	9 18.998 71 4.0 1681 1.696 -188.13 -219.61	1s	2s	2p
		2	2	5

Neon (Ne): Discovered by Ramsay and Travers in 1898. The name is derived from the greek neos, meaning "new". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	10 20.183 71 0.0 2080 0.899944 -246.08	1s	2s	2p
		2	2	6

Sodium (Na): First isolated by Sir Humphrey Davy in 1808. The name is derived from the english word "soda". The symbol is derived from the latin natrium (soda). (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	11 22.990 186 0.9 496 0.968 881.4 97.82	1s	2s	2p	3s	3p	3d
		2	2	6	1

Magnesium (Mg): The name is derived from "Magnesia", a region of Greece. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	12 24.312 160 1.2 738 1.74 1100 651	1s	2s	2p	3s	3p	3d
		2	2	6	2

Aluminium (Al): First isolated by Wohler in 1827. The name is derived from the latin alumen , meaning "alum". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	13 26.982 143 1.5 578 1.74 2327 660	1s	2s	2p	3s	3p	3d
		2	2	6	2	1

Silicon (Si): First prepared by Berzelius in 1824. The name is derived from the latin silex, meaning "flint". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	14 28.086 117 1.8 786 2.35 1410	1s	2s	2p	3s	3p	3d
		2	2	6	2	2

Phosphorus (P): First prepared by Brand in 1669. The name is derived from the Greek phosphoros, "bringer of light". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (white allotrope), (red allotrope) B.Pt at S.P (°C) M.Pt at S.P (°C) (white allotrope)	15 30.974 110 2.1 1012 1.88, 2.34 280 44.1	1s	2s	2p	3s	3p	3d
		2	2	6	2	3

Sulphur (S): Occurs naturally as the free element, and thus known from ancient times. The name is derived from the sanskrit sulvere. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (monoclinic), (orthorhombic) B.Pt at S.P (°C) M.Pt at S.P (°C) (monoclinic)	16 32.064 103 2.5 999 1.96, 2.06 444.6 115.21	1s	2s	2p	3s	3p	3d
		2	2	6	2	4

Chlorine (Cl): Discovered by Scheele in 1774. The name is derived from the Greek chloros, meaning "greenish yellow". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	17 35.453 100 3.0 1255 3.214 -34.55 -101.0	1s	2s	2p	3s	3p	3d
		2	2	6	2	5

Argon (Ar): Discovered by Lord Rayleigh and Sir William Ramsay in 1894. The name is derived from the Greek argos , meaning "inactive". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	18 39.948 98 0.0 1520 1.784 -185.86 -189.2	1s	2s	2p	3s	3p	3d
		2	2	6	2	6

Potassium (K): First prepared by Humphry Davy in 1807. The name is derived from "potash". The symbol stands for kalium, a latin form of the arabic al kali. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	19 39.102 231 0.8 419 0.856 765.5 63.2	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6		1

Calcium (Ca): First obtained in the metallic state by Matthiesen in 1808. The name is derived from the Latin calcx. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	20 40.08 197 1.0 590 1.54 1440 850	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6		2

Scandium (Sc): Discovered by L. F. Nilson in 1879. The element is named after Scandinavia. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	21 44.96 160 1.3 613 2.985 1538	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	1	2

Titanium (Ti): First prepared by M. A. Hunter in 1910. It is named after the Titans of Greek mythology. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (a), (b) B.Pt at S.P (°C) M.Pt at S.P (°C)	22 47.90 145 1.5 656 4.506, 4.400 3277 1677	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	2	2

Vanadium (V): First obtained in the metallic state by Roscoe in 1869. The element is named afted Vanadis, the Scandinavian goddess of beauty. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	23 50.942 131 1.6 650 6.11 1917	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	3	2

Chromium (Cr): Discovered by Vauquelin in 1797. The name is derived from the greek \i chloros \i0 (colour), on account of the colour of its salts. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	24 51.996 125 1.6 653 7.14 2642 1900	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	5	1

Manganese (Mn): Discovered by C W Scheele and isolated by J G Gahn in 1774. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (a), (b) B.Pt at S.P (°C) M.Pt at S.P (°C)	25 54.938 137 1.5 717 7.47, 7.26 2095 1244	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	5	2

Iron (Fe): Known since antiquity. The symbol is derived from ferrum , the Latin name for the element. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	26 55.847 126 1.8 762 7.86 3000 1535	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	6	2

Cobalt (Co): Discovered by Brandt in 1742. The name is deived from the German kobold , meaning a mischievous spirit. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	27 59.933 125 1.8 758 8.92 3100 1493	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	7	2

Nickel (Ni): Isolated in an impure metallic state by A. F. Cronstedt in 1751. It is named after the german word kupfernickel. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	28 58.71 125 1.8 737 8.90 2837 1555	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	8	2

Copper (Cu): Known since antiquity. The symbol is derived from the latin word for the element, cuprum. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	29 63.54 128 1.9 745 8.94 2595 1083	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	1

Zinc (Zn): Known since antiquity. Named from the German zink. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	30 65.37 133 1.6 906 7.14 908 419.5	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2

Gallium (Ga): Discovered by P. E. L de Boisbaudran, who named it after Gallia, the Latin name for Gaul. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	31 69.72 122 1.6 579 5.904 2400 29.78	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2	1

Germanium (Ge): Predicted by D Mendeleyev in 1871 and first isolated by C Winkler in 1886. Named from the Latin name for Germany - Germania. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	32 72.59 123 1.8 760 5.323 937	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2	2

Arsenic (As): First isolated by Albertus Magnus in the 13th century. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt : Sublimes at 616°C at S.P M.Pt at S.P (°C)	33 74.922 124 2.0 947 5.5727	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2	3

Selenium (Se): Discovered by J J Berzelius in 1818. Named from the Greek for "moon", selene. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (metallic form) B.Pt at S.P (°C) M.Pt at S.P (°C) (metallic form)	34 78.96 116 2.4 941 4.81 685 217	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2	4

Bromine (Br): Isolated by A J Balard in 1826. Named from the Greek bromos, which means "stench". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C B.Pt at S.P (°C) M.Pt at S.P (°C)	35 79.909 114 2.8 1142 3.1023 59.47 -7.25	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2	5

Krypton (Kr): Discovered by Sir William Ramsay and M W Travers in 1898. From the greek kruptos, meaning "hidden". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	36 83.80 112 0.0 1351 3.7493 -153.35	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f
		2	2	6	2	6	10	2	6

Rubidium (Rb): Discovered by R W Bunsen and E R Kirchhoff in 1861. It is named from the latin rubidus, meaning "bright red", on account of the colour of its two prominent spectral lines. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

37
85.47
248
0.8
403
1.532
688
39

Strontium (Sr): First prepared hy H Davy in 1808. It is named after the Scottish village Strontian. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

38
87.62
215
1.0
550
2.6
1366
757

Yttrium (Y): Discovered by J Gadolin in 1794. Named after the Swedish village Ytterby. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

39
88.905
178
1.2
615
4.472
3000
1509

Zirconium (Zr): Identified by M H Klaproth in 1789 and first obtained in an impure form by J J Berzelius in 1824. It is named after one of its ores, zircon, (in Arabic: zargun). (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

40
91.22
158
1.4
660
6.5
3577
1857

Niobium (Nb): Discovered by C Hatchett in 1801, who named it columbium (Cb). The name niobium (after the Greek goddess Niobe) was agreed upon in 1949. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

41
92.906
142
1.6
665
8.57
4927
2468

Molybdenum (Mo): Discovered by Scheele in 1778, and prepared by P J Hjelm in 1782. Its name comes from the Greek molybdos, meaning "lead". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

42
95.94
136
1.8
685
10.28
4825
2622

Technetium (Tc): This element does not occur naturally. It was first prepared by E Segr\'e9 and C Perrier in 1937 by bombarding a molybdenum target with deuterons. It was the first element to be prepared artificially. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

43
98
132
1.9
700

Ruthenium (Ru): Discovered by Osann in 1828, and first prepared by C Klaus in 1844. Named from the Latin Ruthenia , meaning "Russia". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

44
101.07
133
2.2
710
12.45
~4150
~2450

Rhodium (Rh): Discovered by W Wollaston in 1804. Named from the Greek rhodos, meaning "red", on account of the colour of many of its salts. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

45
102.91
134
2.2
720
12.41

1966

Palladium (Pd): Discovered by W Wollaston in 1804. Named after the asteroid Pallas. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

46
106.4
138
2.2
805
12.02
3167
1555

Silver (Ag): Known since antiquity. The symbol is derived from the Latin argentum, meaning "silver". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

47
107.87
144
1.9
730
10.49
~2000
960.5

Cadmium (Cd): Discovered by F Strohmeyer and K S L Hermann in 1817. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

48
112.4
149
1.7
870
8.65
7.65
321

Indium (In): Discovered by F Reich and T Richter in 1863. Named after the indigo-blue colour of its spectral lines. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	49 114.82 162 1.7 560 7.3 2000 155	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f
		2	2	6	2	6	10	2	6	10		2	1

Tin (Sn): Known since antiquity. The symbol is derived from its Latin name stannum. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	50 118.69 140 1.8 710 7.31 2507 231.9	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f
		2	2	6	2	6	10	2	6	10		2	2

Antimony (Sb): Known since antiquity, it was first described by Basil Valentine in 1604. Its chemical symbol is derived from the Latin stibium. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	51 121.75 145 1.9 835 6.68 1635 630	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f
		2	2	6	2	6	10	2	6	10		2	3

Tellurium (Te): Discovered by M H Klaproth in 1782. The name is derived from the Latin tellus, meaning "earth". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	52 127.60 143 2.1 870 6.11-6.27 989.9 449.8	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f
		2	2	6	2	6	10	2	6	10		2	4

Iodine (I): Discovered by B Courtois in 1811. The name is derived from the Greek iodes, meaning "violet", on account of the colour of its vapour. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	53 126.9 133 2.5 1010 4.93 185.24 113.6	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f
		2	2	6	2	6	10	2	6	10		2	5

Xenon (Xe): Discovered by W Ramsay and M W Travers in 1898. The name is derived from the Greek xenos, meaning "stranger". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Density at STP (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	54 131.3 131 0.0 1170 5.8971 2507 231.9	1s	2s	2p	3s	3p	3d	4s	4p	4d	4f	5s	5p	5d	5f
		2	2	6	2	6	10	2	6	10		2	6

Cesium (Cs):Discovered by R Bunsen and G R Kirchhoff in 1860. The name is derived from the Latin caesium , "sky blue". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

55
132.905
265
0.7
377
1.873
705
28.5

[Xe]

Barium (Ba): First obtained in the metallic state by R Bunsen in 1854. The name is derived from the Greek barys, meaning "heavy". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

56
137.34
217
0.9
503
3.6
~1600
710

[Xe]

Lanthanum (La): A rare earth element discovered by C G Mosander in 1839. Named from the Greek lanthanein, meaning "to be concealed". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

57
138.91
187
1.1
541
6.2

920

[Xe]

Cerium (Ce): A rare earth element discovered in 1803 by J Berzelius and W Hisinger, and, independently by M H Klaproth. Named after the asteroid Ceres. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

58
140.12
183
1.1
658
6.77

795

[Xe]

Praseodymium (Pr): A rare earth element discovered in 1855 by C A von Welsbach. The name is a shortened form of "praseodidymium", ("green didymium"), after the colour of its salts. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)(a), (b)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

59
140.907
182
1.1
553
6.77, 6.44
3290 ± 90
935

[Xe]

Neodymium (Nd): A rare earth element discovered in 1855 by C A von Welsbach. Named from "neo" ("new"), and "didymium", another rare earth element. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

60
144.24
181
1.1
612
7.003
~3000
1024

[Xe]

Promethium (Pm): A rare earth element isolated by J A Marinsky, L E Glendenin and C D Coryell in 1947. Named after the Greek mythological character Prometheus. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

61
147
181
1.1
553
7.22

1080

[Xe]

Samarium (Sm): Discovered in 1879 by L de Boisbaudran. Named after the mineral samarkite, which in turn was named after the Russian engineer M Samarski. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

62
150.35
181
1.1
545
7.536

1072

[Xe]

Europium (Eu): A rare earth element discovered in 1896 by E Demarçay. Named for Europe. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

63
151.96
199
1.1
549
5.244

826

[Xe]

Gadolinium (Gd): A rare earth element whose discovery is credited to J C G de Marignac (1880) and L de Boisbaudran (1886). Named after the Finnish chemist J Gadolin. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

64
157.25
179
1.1
591
7.886

~604

[Xe]

Terbium (Tb): A rare earth element discovered in 1843 by C G Mosander. Named after the Swedish town Ytterby. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

65
158.924
176
1.2
649
8.27

1356

[Xe]

Dysprosium (Dy): A rare earth element whose existence was proved in 1886 by L de Boisbaudran. Purified by G Urbain in 1906. Named from the Greek dysprositos, meaning "hard to get at".(Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

66
162.5
175
1.2
654
8.559

1407

[Xe]

Holmium (Ho): A rare earth element discovered independently by J L Soret (1878) and P T Cleve (1879). Named from the Latinized form for Stockholm, Holmia. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

67
164.93
174
1.2

8.799

1461

[Xe]

Erbium (Er): A rare earth element discovered in 1843 by C G Mosander. Named after the Swedish town Ytterby. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

68
167.26
173
1.2
587
9.062

1497

[Xe]

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

69
168.934
172
1.2
561
9.322

1545

[Xe]

Ytterbium (Yb): A rare earth element discovered by J C G de Marignac in 1878, and named after the Swedish town Ytterby. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

70
173.04
194
1.2
595
6.977

824

[Xe]

Lutetium (Lu): A rare earth element discovered independently by C A von Welsbach (1907) and G Urbain (1908). Named after the Roman name for Paris, Lutetia. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

71
174.97
171
1.2
591
9.842

1652

[Xe]

Hafnium (Hf): Discovered by D Coster and G C de Hevesy in 1923. Named from the Latin for Copenhagen, where it was discovered. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

72
178.49
157
1.3
675
13.3

2227

[Xe]

Tantalum (Ta): Discovered by A G Ekeberg in 1802. Named after the mythological character Tantalus. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

73
180.95
143
1.5
760
16.69
5429
2996

[Xe]

Tungsten (W): First prepared in the metallic state by J J and F d' Elhuyar in 1783. The name tungsten comes from the Swedish tung (heavy) and sten (stone). The symbol is derived from the German wolfram. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

74
183.85
127
1.7
770
18.7-19.3
5900
3410

[Xe]

Rhenium (Re): Discovered by I and W Noddack in 1925. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

75
186.2
137
1.9
758
10.4
~5900
3180

[Xe]

Osmium (Os): First prepared by S Tennant in 1804. The name is derived from the Greek osme, meaning "smell". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

76
190.2
134
2.2
820
22.61
~5500
~2700

[Xe]

Iridium (Ir): Discovered by S Tennant in 1804. It is named on account of the various colours of its compounds. It has the distinction of having the highest specific gravity of all elements. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

77
192.2
136
2.2
875
22.65
~4500
2450

[Xe]

Platinum (Pt): Known from antiquity. The name is derived from Old Spanish platina, meaning "silver". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

78
195.09
139
2.2
868
21.4
~3827
1775

[Xe]

Gold (Au): Known from antiquity. The symbol is derived from the Latin name for the metal, aurum. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

79
196.97
144
2.4
890
19.3
2700
1065

[Xe]

Mercury (Hg): Known since antiquity. The symbol is derived from the Latin hydrargyrum, meaning "liquid silver". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

80
200.59
151
1.9
1006
12.534
356.72
-38.87

[Xe]

Thallium (Tl): Identified as an element in 1861 by W Crookes, and isolated by Claude-Auguste in 1862. The name is derived from the Greek for "green twig", on account of a prominent green line in its spectrum. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

81
204.37
170
1.8
587
11.85
1457
303.5

[Xe]

Lead (Pb): Known since antiquity. The symbol is derived from the Latin name for the metal, plumbum. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

82
207.19
175
1.8
716
11.34
1740
327.4

[Xe]

Bismuth (Bi): First described by the alchemist Basil Valentine sometime in the 15th century. The name is probably derived from Old German weissmuth, meaning "white matter". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

83
208.98
155
1.9
704
9.78
1420
271

[Xe]

Polonium (Po): Discovered by Pierre and Marie Curie in 1898, and named after Poland, Marie's native land. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3) (a), (b)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

84
210
167
2.0
813
9.196, 9.398
962
254

[Xe]

Astatine (At): A synthetic element first prepared by D R Corson, K R Mackenzie and E Segré in 1940. It is named from the Greek astatos, meaning "unstable". (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Specific gravity at 20 °C (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

85
210

2.2
917

[Xe]

Radon (Rn): Discovered by F E Dorn in 1900. Named after the element Radium, from which it is produced by radioactive decay. (Back to the Periodic Table)

Properties

Electronic Structure

Atomic number
Atomic mass
Atomic radius (pm)
Electronegativity
1st Ionization energy (kJ.mol^-1)
Density at STP (g.dm^-3)
B.Pt at S.P (°C)
M.Pt at S.P (°C)

86
222

0.0
1035
9.73
-62

[Xe]

Francium (Fr): Isolated in 1939 by M Perey. Named after France. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	87 223 270 0.7 386	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86				1

Radium (Ra): Discovered by P Curie, M Curie and G Bémont in 1898, and first obtained as a metal in 1910 by M Curie and A Debierne. Its name is derived from the fact that it is radioactive. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	88 226.025 220 0.9 511 5.5 1737 700	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86				2

Actinium (Ac): The first member of the actinide series of the elements, it was discovered independently by A Debierne (1899) and F O Griesel (1902). Its name is derived from the Greek aktinos, meaning "ray". (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	89 227 200 1.1 666 10.07 3300 1050	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86		1		2

Thorium (Th): An actinide element first identified in 1828 by J Berzelius. Named after Thor, the Scandinavian god of war. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	90 232.04 1.3 671 11.3-11.7 1842 ± 30	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86		2		2

Protactinium (Pa): A member of the actinide series of elements, it was discovered by K Fajans and O H Göring in 1913. Its name is based on the fact that it gives rise to actinium by radioactive decay. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	91 231.0 1.5 15.37 1560	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	2	1		2

Uranium (U): A member of the actinide series of elements, it was discovered in 1789 by M H Klaproth. It is named after the planet Uranus. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	92 238.03 175 377 19 ~1132	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	3	1		2

Neptunium (Np): A member of the actinide series of elements, and a so-called transuranium element, it was discovered by E M McMillan and P H Abelson in 1940. It is named after the planet Neptune. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	93 237 1.3 20.45 640	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	5			2

Plutonium (Pu): A member of the actinide series of elements, and a so-called transuranium element, it was produced synthetically in 1940 by G T Seaborg, A C Wahl, J W Kennedy and E Segré. It is named after the planet Pluto. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	94 242 1.3 19.816 639.5	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	6			2

Americium (Am): A member of the actinide series of elements, and a so-called transuranium element, first produced by G T Seaborg and his co-workers in 1944. It is named after the United States of America. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	95 243 1.3 13.67 1175	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	7			2

Curium (Cm): A member of the actinide series of elements, and a so-called transuranium element, first produced by G T Seaborg and his co-workers in 1944. It is named after the Curies, who discovered Polonium and Radium. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	96 247 1.3 13.51 1350 ± 50	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	7	1		2

Berkelium (Bk): A member of the actinide series of elements, and a so-called transuranium element, first produced by G T Seaborg, S G Thompson and A Ghioso in 1949. It is named after the University of California at Berkeley. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3)(a), (b) B.Pt at S.P (°C) M.Pt at S.P (°C)	97 247 1.3 14.78, 13.25 986 ± 25	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	8	1		2

Californium (Cf): A member of the actinide series of elements, and a so-called transuranium element, first produced by A Ghioso and his co-workers in 1952. It is named after California. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	98 252 1.3 900 ± 30	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	10			2

Einsteinium (Es): A member of the actinide series of elements, and a so-called transuranium element. It was produced synthetically in 1955 by A Ghiorso, B G Harvey, G R Choppin, S G Thompson and G T Seaborg. It is named in honour of the physicist Albert Einstein (1879 - 1955). (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	99 254 1.3	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	11			2

Fermium (Fm): A member of the actinide series of elements, and a so-called transuranium element. It was produced synthetically in 1955 by A Ghiorso, B G Harvey, G R Chop pin, S G Thompson and G T Seaborg. It is named in honour of the physicist Enrico Fermi (1901 - 1954), the inventor of the atomic pile. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	100 253 1.3	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	12			2

Mendelevium (Md): A member of the actinide series of elements, and a so-called transuranium element. It was produced synthetically in 1955 by A Ghiorso, B G Harvey, G R Choppin, S G Thompson and G T Seaborg. It is named in honour of the Russian chemist Dimitri Mendeleev, (1834 - 1907), who proposed the modern periodic classification of the elements. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	101 256	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	13			2

Nobelium (No): A member of the actinide series of elements, and a so-called transuranium element. It was produced synthetically in 1958 by A Ghiorso, T Sikkeland, J R Walton and G T Seaborg. It is named in honour of the Swedish chemist Alfred Nobel (1833 - 1896), founder of the Nobel Prizes. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	102 254 1.3	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	13	1		2

Lawrencium (Lr): A member of the actinide series of elements, and a so-called transuranium element. It was produced synthetically in 1961 by A Ghiorso, T Sikkeland, A E Larsh and R M Latimer. It is named in honour of the physicist E O Lawrence (1901 - 1958), inventor of the cyclotron. (Back to the Periodic Table)

Properties		Electronic Structure
Atomic number Atomic mass Atomic radius (pm) Electronegativity 1st Ionization energy (kJ.mol^-1) Specific gravity at 20 °C (g.dm^-3) B.Pt at S.P (°C) M.Pt at S.P (°C)	103 257 1.3	[Rn]	5f	6d	6f	7s	7p	7d	7f
		86	14	1		2

Rutherfordium (Rf): (Atomic number 104) Named after the physicist Ernest Rutherford (1871 - 1937).

Dubnium (Db): (Atomic number 105) Named for the achievements of the Joint Institute for Nuclear Research at Dubna, Russia.

Seaborgium (Sg): (Atomic number 106) Named after Glenn Seaborg (1912 - 1999) who first synthesized transuranium elements.

Bohrium (Bh): (Atomic number 107) Named after Niels Bohr (1885 - 1962), a pioneer in the use of applying the Quantum Theory to atomic structure.

Hassium (Hs): (Atomic number 108) Named after the latinized name for Hesse province of Germany, where considerable research was carried out on the synthesis of transuranium elements.

Meitnerium (Mt): (Atomic number 109) Named after the nuclear physicist Lise Meitner (1878 - 1968).

Darmstadtium (Ds): (Atomic number 110) Named after the German city of Darmstadt.

Roentgenium (Rg): (Atomic number 111) Named after the discoverer of X-rays, Wilhelm Conrad Röntgen (1878 - 1968).

Inert gases: The inert gases (also known as the rare gases, noble gases, or Group 18 elements) all have an outer electronic configuration s²p⁶. They are chemically unreactive, although the heavier members such as Xe form unstable compounds with fluorine. (Back to the Periodic Table)

Alkali metals: The alkali metals, or Group 1 elements, are reactive metals forming cations M⁺. They all have an outer electronic configuration s¹. (Back to the Periodic Table)

Alkaline earths: The alkaline earth metals, or Group 2 elements, are metals tending to form cations M²⁺. They all have an outer electronic configuration s². (Back to the Periodic Table)

Chalcogens: The group 16 elements, sometimes referred to as the chalcogens, all have an outer electronic configuration s²p⁴. (Back to the Periodic Table)

Halogens: The halogens, or Group17 elements, all have an outer electronic configuration s²p⁵. They are reactive, and tend to form anions of the type X^-. (Back to the Periodic Table)

Lanthanides: The lanthanides, or rare earth elements, are a series of elements with closely related properties in which the 4f shell is progressively filled. This family of elements fit in the empty Group 3 space in the Periodic Table, between Ba and Hf. Together with the actinides (described below), they form the f-block of elements. (Back to the Periodic Table)

Actinides: The actinides are a series of elements in which the 5f shell is progressively filled. This family of elements fit in the empty Group 3 space in the Periodic Table, between Ra and Rf. The elements with atomic numbers 93 (plutonium) and higher do not occur naturally, and are often referred to as the transuranium elements. They are all radioactive to some degree. Together with the lanthanides (described above), they form the f-block of elements.(Back to the Periodic Table)


See also:	Inert gases Alkali metals Alkaline earths Chalcogens Halogens

THE PERIODIC TABLE OF THE ELEMENTS