periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled Periodic Table).

There are 18 vertical columns, or groups, in the standard periodic table. At present, there are three versions of the periodic table, each with its own unique column headings, in wide use. The three formats are the old International Union of Pure and Applied Chemistry (IUPAC) table, the Chemical Abstract Service (CAS) table, and the new IUPAC table. The old IUPAC system labeled columns with Roman numerals followed by either the letter A or B. Columns 1 through 7 were numbered IA through VIIA, columns 8 through 10 were labeled VIIIA, columns 11 through 17 were numbered IB through VIIB and column 18 was numbered VIII. The CAS system also used Roman numerals followed by an A or B. This method, however, labeled columns 1 and 2 as IA and IIA, columns 3 through 7 as IIIB through VIB, column 8 through 10 as VIII, columns 11 and 12 as IB and IIB and columns 13 through 18 as IIIA through VIIIA. However, in the old IUPAC system the letters A and B were designated to the left and right part of the table, while in the CAS system the letters A and B were designated to the main group elements and transition elements respectively. (The preparer of the table arbitrarily could use either an upper-or lower-case letter A or B, adding to the confusion.) Further, the old IUPAC system was more frequently used in Europe while the CAS system was most common in America. In the new IUPAC system, columns are numbered with Arabic numerals from 1 to 18. These group numbers correspond to the number of s, p, and d orbital electrons added since the last noble gas element (in column 18). This is in keeping with current interpretations of the periodic law which holds that the elements in a group have similar configurations of the outermost electron shells of their atoms. Since most chemical properties result from outer electron interactions, this tends to explain why elements in the same group exhibit similar physical and chemical properties. Unfortunately, the system fails for the elements in the first 3 periods (or rows; see below). For example, aluminum, in the column numbered 13, has only 3 s, p, and d orbital electrons. Nevertheless, the American Chemical Society has adopted the new IUPAC system.

The horizontal rows of the table are called periods. The elements of a period are characterized by the fact that they have the same number of electron shells; the number of electrons in these shells, which equals the element's atomic number, increases from left to right within each period. In each period the lighter metals appear on the left, the heavier metals in the center, and the nonmetals on the right. Elements on the borderline between metals and nonmetals are called metalloids.

Group 1 (with one valence electron) and Group 2 (with two valence electrons) are called the alkali metals and the alkaline-earth metals, respectively. Two series of elements branch off from Group 3, which contains the transition elements, or transition metals; elements 57 to 71 are called the lanthanide series, or rare earths, and elements 89 to 103 are called the actinide series, or radioactive rare earths; a third set, the superactinide series (elements 122-153), is predicted to fall outside the main body of the table, but none of these has yet been synthesized or isolated. The nonmetals in Group 17 (with seven valence electrons) are called the halogens. The elements grouped in the final column (Group 18) have no valence electrons and are called the inert gases, or noble gases, because they react chemically only with extreme difficulty.

In a relatively simple type of periodic table, each position gives the name and chemical symbol for the element assigned to that position; its atomic number; its atomic weight (the weighted average of the masses of its stable isotopes, based on a scale in which carbon-12 has a mass of 12); and its electron configuration, i.e., the distribution of its electrons by shells. The only exceptions are the positions of elements 103 through 118; complete information on these elements has not been compiled. Larger and more complicated periodic tables may also include the following information for each element: atomic diameter or radius; common valence numbers or oxidation states; melting point; boiling point; density; specific heat; Young's modulus; the quantum states of its valence electrons; type of crystal form; stable and radioactive isotopes; and type of magnetism exhibited by the element (paramagnetism or diamagnetism).

Atomic Number:	Atomic Number: 40
Atomic Symbol:	Atomic Symbol: Zr
	Name of Element: Zirconium
Atomic Weight:	Atomic Weight: 91.22
Electron Configuration:	Electron Configuration: 2 · 8 · 1810 · 2

Atomic Number:	Atomic Number: 30
Atomic Symbol:	Atomic Symbol: Zn
	Name of Element: Zinc
Atomic Weight:	Atomic Weight: 65.38
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 2

Atomic Number:	Atomic Number: 39
Atomic Symbol:	Atomic Symbol: Y
	Name of Element: Yttrium
Atomic Weight:	Atomic Weight: 88.9059
Electron Configuration:	Electron Configuration: 2 · 8 · 189 · 2

Atomic Number:	Atomic Number: 70
Atomic Symbol:	Atomic Symbol: Yb
	Name of Element: Ytterbium
Atomic Weight:	Atomic Weight: 173.04
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 8 · 2

Atomic Number:	Atomic Number: 54
Atomic Symbol:	Atomic Symbol: Xe
	Name of Element: Xenon
Atomic Weight:	Atomic Weight: 131.29
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 8

Atomic Number:	Atomic Number: 23
Atomic Symbol:	Atomic Symbol: V
	Name of Element: Vanadium
Atomic Weight:	Atomic Weight: 50.9415
Electron Configuration:	Electron Configuration: 2 · 8 · 11 · 2

Atomic Number:	Atomic Number: 92
Atomic Symbol:	Atomic Symbol: U
	Name of Element: Uranium
Atomic Weight:	Atomic Weight: 238.0289
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 219 · 2

Atomic Number:	Atomic Number: 113
Atomic Symbol:	Atomic Symbol: Uut
	Name of Element: Ununtrium
Atomic Weight:	Atomic Weight: (284)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 6

Atomic Number:	Atomic Number: 114
Atomic Symbol:	Atomic Symbol: Uuq
	Name of Element: Ununquadium
Atomic Weight:	Atomic Weight: (289)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 4

Atomic Number:	Atomic Number: 115
Atomic Symbol:	Atomic Symbol: Uup
	Name of Element: Ununpentium
Atomic Weight:	Atomic Weight: (288)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 6

Atomic Number:	Atomic Number: 118
Atomic Symbol:	Atomic Symbol: Uuo
	Name of Element: Ununoctium
Atomic Weight:	Atomic Weight: (294)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 8

Atomic Number:	Atomic Number: 116
Atomic Symbol:	Atomic Symbol: Uuh
	Name of Element: Ununhexium
Atomic Weight:	Atomic Weight: (292)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 6

Atomic Number:	Atomic Number: 112
Atomic Symbol:	Atomic Symbol: Uub
	Name of Element: Ununbium
Atomic Weight:	Atomic Weight: (285)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 2

Atomic Number:	Atomic Number: 74
Atomic Symbol:	Atomic Symbol: W
	Name of Element: Tungsten
Atomic Weight:	Atomic Weight: 183.85
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 12 · 2

Atomic Number:	Atomic Number: 22
Atomic Symbol:	Atomic Symbol: Ti
	Name of Element: Titanium
Atomic Weight:	Atomic Weight: 47.88
Electron Configuration:	Electron Configuration: 2 · 8 · 10 · 2

Atomic Number:	Atomic Number: 50
Atomic Symbol:	Atomic Symbol: Sn
	Name of Element: Tin
Atomic Weight:	Atomic Weight: 118.69
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 4

Atomic Number:	Atomic Number: 69
Atomic Symbol:	Atomic Symbol: Tm
	Name of Element: Thulium
Atomic Weight:	Atomic Weight: 168.9342
Electron Configuration:	Electron Configuration: 2 · 8 · 1831 · 8 · 2

Atomic Number:	Atomic Number: 90
Atomic Symbol:	Atomic Symbol: Th
	Name of Element: Thorium
Atomic Weight:	Atomic Weight: 232.0381
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 1810 · 2

Atomic Number:	Atomic Number: 81
Atomic Symbol:	Atomic Symbol: Tl
	Name of Element: Thallium
Atomic Weight:	Atomic Weight: 204.383
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 3

Atomic Number:	Atomic Number: 65
Atomic Symbol:	Atomic Symbol: Tb
	Name of Element: Terbium
Atomic Weight:	Atomic Weight: 158.9254
Electron Configuration:	Electron Configuration: 2 · 8 · 1827 · 8 · 2

Atomic Number:	Atomic Number: 52
Atomic Symbol:	Atomic Symbol: Te
	Name of Element: Tellurium
Atomic Weight:	Atomic Weight: 127.60
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 6

Atomic Number:	Atomic Number: 43
Atomic Symbol:	Atomic Symbol: Tc
	Name of Element: Technetium
Atomic Weight:	Atomic Weight: (98)
Electron Configuration:	Electron Configuration: 2 · 8 · 1813 · 2

Atomic Number:	Atomic Number: 73
Atomic Symbol:	Atomic Symbol: Ta
	Name of Element: Tantalum
Atomic Weight:	Atomic Weight: 180.9479
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 11 · 2

Atomic Number:	Atomic Number: 16
Atomic Symbol:	Atomic Symbol: S
	Name of Element: Sulfur
Atomic Weight:	Atomic Weight: 32.06
Electron Configuration:	Electron Configuration: 2 · 8 · 6

Atomic Number:	Atomic Number: 38
Atomic Symbol:	Atomic Symbol: Sr
	Name of Element: Strontium
Atomic Weight:	Atomic Weight: 87.62
Electron Configuration:	Electron Configuration: 2 · 8 · 188 · 2

Atomic Number:	Atomic Number: 11
Atomic Symbol:	Atomic Symbol: Na
	Name of Element: Sodium
Atomic Weight:	Atomic Weight: 22.98977
Electron Configuration:	Electron Configuration: 2 · 8 · 1

Atomic Number:	Atomic Number: 47
Atomic Symbol:	Atomic Symbol: Ag
	Name of Element: Silver
Atomic Weight:	Atomic Weight: 107.8682
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 1

Atomic Number:	Atomic Number: 14
Atomic Symbol:	Atomic Symbol: Si
	Name of Element: Silicon
Atomic Weight:	Atomic Weight: 28.0855
Electron Configuration:	Electron Configuration: 2 · 8 · 4

Atomic Number:	Atomic Number: 34
Atomic Symbol:	Atomic Symbol: Se
	Name of Element: Selenium
Atomic Weight:	Atomic Weight: 78.96
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 6

Atomic Number:	Atomic Number: 106
Atomic Symbol:	Atomic Symbol: Sg
	Name of Element: Seaborgium
Atomic Weight:	Atomic Weight: (266)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3212 · 2

Atomic Number:	Atomic Number: 21
Atomic Symbol:	Atomic Symbol: Sc
	Name of Element: Scandium
Atomic Weight:	Atomic Weight: 44.9559
Electron Configuration:	Electron Configuration: 2 · 8 · 9 · 2

Atomic Number:	Atomic Number: 62
Atomic Symbol:	Atomic Symbol: Sm
	Name of Element: Samarium
Atomic Weight:	Atomic Weight: 150.36
Electron Configuration:	Electron Configuration: 2 · 8 · 1824 · 8 · 2

Atomic Number:	Atomic Number: 104
Atomic Symbol:	Atomic Symbol: Rf
	Name of Element: Rutherfordium
Atomic Weight:	Atomic Weight: (261)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3210 · 2

Atomic Number:	Atomic Number: 44
Atomic Symbol:	Atomic Symbol: Ru
	Name of Element: Ruthenium
Atomic Weight:	Atomic Weight: 101.07
Electron Configuration:	Electron Configuration: 2 · 8 · 1815 · 1

Atomic Number:	Atomic Number: 37
Atomic Symbol:	Atomic Symbol: Rb
	Name of Element: Rubidium
Atomic Weight:	Atomic Weight: 85.4678
Electron Configuration:	Electron Configuration: 2 · 8 · 188 · 1

Atomic Number:	Atomic Number: 111
Atomic Symbol:	Atomic Symbol: Rg
	Name of Element: Roentgenium
Atomic Weight:	Atomic Weight: (272)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3218 · 1

Atomic Number:	Atomic Number: 45
Atomic Symbol:	Atomic Symbol: Rh
	Name of Element: Rhodium
Atomic Weight:	Atomic Weight: 102.9055
Electron Configuration:	Electron Configuration: 2 · 8 · 1816 · 1

Atomic Number:	Atomic Number: 75
Atomic Symbol:	Atomic Symbol: Re
	Name of Element: Rhenium
Atomic Weight:	Atomic Weight: 186.207
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 13 · 2

Atomic Number:	Atomic Number: 86
Atomic Symbol:	Atomic Symbol: Rn
	Name of Element: Radon
Atomic Weight:	Atomic Weight: (222)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 8

Atomic Number:	Atomic Number: 88
Atomic Symbol:	Atomic Symbol: Ra
	Name of Element: Radium
Atomic Weight:	Atomic Weight: 226.0254
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 188 · 2

Atomic Number:	Atomic Number: 91
Atomic Symbol:	Atomic Symbol: Pa
	Name of Element: Protactinium
Atomic Weight:	Atomic Weight: 231.0359
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 209 · 2

Atomic Number:	Atomic Number: 61
Atomic Symbol:	Atomic Symbol: Pm
	Name of Element: Promethium
Atomic Weight:	Atomic Weight: (145)
Electron Configuration:	Electron Configuration: 2 · 8 · 1823 · 8 · 2

Atomic Number:	Atomic Number: 59
Atomic Symbol:	Atomic Symbol: Pr
	Name of Element: Praseodymium
Atomic Weight:	Atomic Weight: 140.9077
Electron Configuration:	Electron Configuration: 2 · 8 · 1821 · 8 · 2

Atomic Number:	Atomic Number: 19
Atomic Symbol:	Atomic Symbol: K
	Name of Element: Potassium
Atomic Weight:	Atomic Weight: 39.0983
Electron Configuration:	Electron Configuration: 2 · 8 · 8 · 1

Atomic Number:	Atomic Number: 84
Atomic Symbol:	Atomic Symbol: Po
	Name of Element: Polonium
Atomic Weight:	Atomic Weight: (209)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 6

Atomic Number:	Atomic Number: 94
Atomic Symbol:	Atomic Symbol: Pu
	Name of Element: Plutonium
Atomic Weight:	Atomic Weight: (244)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 248 · 2

Atomic Number:	Atomic Number: 78
Atomic Symbol:	Atomic Symbol: Pt
	Name of Element: Platinum
Atomic Weight:	Atomic Weight: 195.08
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 16 · 2

Atomic Number:	Atomic Number: 15
Atomic Symbol:	Atomic Symbol: P
	Name of Element: Phosphorus
Atomic Weight:	Atomic Weight: 30.97376
Electron Configuration:	Electron Configuration: 2 · 8 · 5

Atomic Number:	Atomic Number: 46
Atomic Symbol:	Atomic Symbol: Pd
	Name of Element: Palladium
Atomic Weight:	Atomic Weight: 106.42
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 0

Atomic Number:	Atomic Number: 8
Atomic Symbol:	Atomic Symbol: O
	Name of Element: Oxygen
Atomic Weight:	Atomic Weight: 15.9994
Electron Configuration:	Electron Configuration: 2 · 6

Atomic Number:	Atomic Number: 76
Atomic Symbol:	Atomic Symbol: Os
	Name of Element: Osmium
Atomic Weight:	Atomic Weight: 190.2
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 14 · 2

Atomic Number:	Atomic Number: 102
Atomic Symbol:	Atomic Symbol: No
	Name of Element: Nobelium
Atomic Weight:	Atomic Weight: (259)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 328 · 2

Atomic Number:	Atomic Number: 7
Atomic Symbol:	Atomic Symbol: N
	Name of Element: Nitrogen
Atomic Weight:	Atomic Weight: 14.0067
Electron Configuration:	Electron Configuration: 2 · 5

Atomic Number:	Atomic Number: 41
Atomic Symbol:	Atomic Symbol: Nb
	Name of Element: Niobium
Atomic Weight:	Atomic Weight: 92.9064
Electron Configuration:	Electron Configuration: 2 · 8 · 1812 · 1

Atomic Number:	Atomic Number: 28
Atomic Symbol:	Atomic Symbol: Ni
	Name of Element: Nickel
Atomic Weight:	Atomic Weight: 58.69
Electron Configuration:	Electron Configuration: 2 · 8 · 16 · 2

Atomic Number:	Atomic Number: 93
Atomic Symbol:	Atomic Symbol: Np
	Name of Element: Neptunium
Atomic Weight:	Atomic Weight: 237.0482
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 229 · 2

Atomic Number:	Atomic Number: 10
Atomic Symbol:	Atomic Symbol: Ne
	Name of Element: Neon
Atomic Weight:	Atomic Weight: 20.179
Electron Configuration:	Electron Configuration: 2 · 8

Atomic Number:	Atomic Number: 60
Atomic Symbol:	Atomic Symbol: Nd
	Name of Element: Neodymium
Atomic Weight:	Atomic Weight: 144.24
Electron Configuration:	Electron Configuration: 2 · 8 · 1822 · 8 · 2

Atomic Number:	Atomic Number: 42
Atomic Symbol:	Atomic Symbol: Mo
	Name of Element: Molybdenum
Atomic Weight:	Atomic Weight: 95.94
Electron Configuration:	Electron Configuration: 2 · 8 · 1813 · 1

Atomic Number:	Atomic Number: 80
Atomic Symbol:	Atomic Symbol: Hg
	Name of Element: Mercury
Atomic Weight:	Atomic Weight: 200.59
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 2

Atomic Number:	Atomic Number: 101
Atomic Symbol:	Atomic Symbol: Md
	Name of Element: Mendelevium
Atomic Weight:	Atomic Weight: (258)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 318 · 2

Atomic Number:	Atomic Number: 109
Atomic Symbol:	Atomic Symbol: Mt
	Name of Element: Meitnerium
Atomic Weight:	Atomic Weight: (266)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3215 · 2

Atomic Number:	Atomic Number: 25
Atomic Symbol:	Atomic Symbol: Mn
	Name of Element: Manganese
Atomic Weight:	Atomic Weight: 54.9380
Electron Configuration:	Electron Configuration: 2 · 8 · 13 · 2

Atomic Number:	Atomic Number: 12
Atomic Symbol:	Atomic Symbol: Mg
	Name of Element: Magnesium
Atomic Weight:	Atomic Weight: 24.305
Electron Configuration:	Electron Configuration: 2 · 8 · 2

Atomic Number:	Atomic Number: 71
Atomic Symbol:	Atomic Symbol: Lu
	Name of Element: Lutetium
Atomic Weight:	Atomic Weight: 174.967
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 9 · 2

Atomic Number:	Atomic Number: 3
Atomic Symbol:	Atomic Symbol: Li
	Name of Element: Lithium
Atomic Weight:	Atomic Weight: 6.941
Electron Configuration:	Electron Configuration: 2 · 1

Atomic Number:	Atomic Number: 82
Atomic Symbol:	Atomic Symbol: Pb
	Name of Element: Lead
Atomic Weight:	Atomic Weight: 207.2
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 4

Atomic Number:	Atomic Number: 103
Atomic Symbol:	Atomic Symbol: Lr
	Name of Element: Lawrencium
Atomic Weight:	Atomic Weight: (262)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 329 · 2

Atomic Number:	Atomic Number: 57
Atomic Symbol:	Atomic Symbol: La
	Name of Element: Lanthanum
Atomic Weight:	Atomic Weight: 138.9055
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 9 · 2

Atomic Number:	Atomic Number: 36
Atomic Symbol:	Atomic Symbol: Kr
	Name of Element: Krypton
Atomic Weight:	Atomic Weight: 83.80
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 8

Atomic Number:	Atomic Number: 26
Atomic Symbol:	Atomic Symbol: Fe
	Name of Element: Iron
Atomic Weight:	Atomic Weight: 55.845
Electron Configuration:	Electron Configuration: 2 · 8 · 14 · 2

Atomic Number:	Atomic Number: 77
Atomic Symbol:	Atomic Symbol: Ir
	Name of Element: Iridium
Atomic Weight:	Atomic Weight: 192.22
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 15 · 2

Atomic Number:	Atomic Number: 53
Atomic Symbol:	Atomic Symbol: I
	Name of Element: Iodine
Atomic Weight:	Atomic Weight: 126.9045
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 7

Atomic Number:	Atomic Number: 49
Atomic Symbol:	Atomic Symbol: In
	Name of Element: Indium
Atomic Weight:	Atomic Weight: 114.82
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 3

Atomic Number:	Atomic Number: 1
Atomic Symbol:	Atomic Symbol: H
	Name of Element: Hydrogen
Atomic Weight:	Atomic Weight: 1.00794
Electron Configuration:	Electron Configuration: 1

Atomic Number:	Atomic Number: 67
Atomic Symbol:	Atomic Symbol: Ho
	Name of Element: Holmium
Atomic Weight:	Atomic Weight: 164.9304
Electron Configuration:	Electron Configuration: 2 · 8 · 1829 · 8 · 2

Atomic Number:	Atomic Number: 2
Atomic Symbol:	Atomic Symbol: He
	Name of Element: Helium
Atomic Weight:	Atomic Weight: 4.0026
Electron Configuration:	Electron Configuration: 2

Atomic Number:	Atomic Number: 108
Atomic Symbol:	Atomic Symbol: Hs
	Name of Element: Hassium
Atomic Weight:	Atomic Weight: (265)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3214 · 2

Atomic Number:	Atomic Number: 72
Atomic Symbol:	Atomic Symbol: Hf
	Name of Element: Hafnium
Atomic Weight:	Atomic Weight: 178.49
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 10 · 2

Atomic Number:	Atomic Number: 79
Atomic Symbol:	Atomic Symbol: Au
	Name of Element: Gold
Atomic Weight:	Atomic Weight: 196.9665
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 1

Atomic Number:	Atomic Number: 32
Atomic Symbol:	Atomic Symbol: Ge
	Name of Element: Germanium
Atomic Weight:	Atomic Weight: 72.59
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 4

Atomic Number:	Atomic Number: 31
Atomic Symbol:	Atomic Symbol: Ga
	Name of Element: Gallium
Atomic Weight:	Atomic Weight: 69.72
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 3

Atomic Number:	Atomic Number: 64
Atomic Symbol:	Atomic Symbol: Gd
	Name of Element: Gadolinium
Atomic Weight:	Atomic Weight: 157.25
Electron Configuration:	Electron Configuration: 2 · 8 · 1825 · 9 · 2

Atomic Number:	Atomic Number: 87
Atomic Symbol:	Atomic Symbol: Fr
	Name of Element: Francium
Atomic Weight:	Atomic Weight: (223)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 188 · 1

Atomic Number:	Atomic Number: 9
Atomic Symbol:	Atomic Symbol: F
	Name of Element: Fluorine
Atomic Weight:	Atomic Weight: 18.998403
Electron Configuration:	Electron Configuration: 2 · 7

Atomic Number:	Atomic Number: 100
Atomic Symbol:	Atomic Symbol: Fm
	Name of Element: Fermium
Atomic Weight:	Atomic Weight: (257)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 308 · 2

Atomic Number:	Atomic Number: 63
Atomic Symbol:	Atomic Symbol: Eu
	Name of Element: Europium
Atomic Weight:	Atomic Weight: 151.96
Electron Configuration:	Electron Configuration: 2 · 8 · 1825 · 8 · 2

Atomic Number:	Atomic Number: 68
Atomic Symbol:	Atomic Symbol: Er
	Name of Element: Erbium
Atomic Weight:	Atomic Weight: 167.26
Electron Configuration:	Electron Configuration: 2 · 8 · 1830 · 8 · 2

Atomic Number:	Atomic Number: 99
Atomic Symbol:	Atomic Symbol: Es
	Name of Element: Einsteinium
Atomic Weight:	Atomic Weight: (252)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 298 · 2

Atomic Number:	Atomic Number: 66
Atomic Symbol:	Atomic Symbol: Dy
	Name of Element: Dysprosium
Atomic Weight:	Atomic Weight: 162.50
Electron Configuration:	Electron Configuration: 2 · 8 · 1828 · 8 · 2

Atomic Number:	Atomic Number: 105
Atomic Symbol:	Atomic Symbol: Db
	Name of Element: Dubnium
Atomic Weight:	Atomic Weight: (262)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3211 · 2

Atomic Number:	Atomic Number: 110
Atomic Symbol:	Atomic Symbol: Ds
	Name of Element: Darmstadtium
Atomic Weight:	Atomic Weight: (271)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3217 · 1

Atomic Number:	Atomic Number: 96
Atomic Symbol:	Atomic Symbol: Cm
	Name of Element: Curium
Atomic Weight:	Atomic Weight: (247)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 259 · 2

Atomic Number:	Atomic Number: 29
Atomic Symbol:	Atomic Symbol: Cu
	Name of Element: Copper
Atomic Weight:	Atomic Weight: 63.546
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 1

Atomic Number:	Atomic Number: 27
Atomic Symbol:	Atomic Symbol: Co
	Name of Element: Cobalt
Atomic Weight:	Atomic Weight: 58.9332
Electron Configuration:	Electron Configuration: 2 · 8 · 15 · 2

Atomic Number:	Atomic Number: 24
Atomic Symbol:	Atomic Symbol: Cr
	Name of Element: Chromium
Atomic Weight:	Atomic Weight: 51.996
Electron Configuration:	Electron Configuration: 2 · 8 · 13 · 1

Atomic Number:	Atomic Number: 17
Atomic Symbol:	Atomic Symbol: Cl
	Name of Element: Chlorine
Atomic Weight:	Atomic Weight: 35.453
Electron Configuration:	Electron Configuration: 2 · 8 · 7

Atomic Number:	Atomic Number: 55
Atomic Symbol:	Atomic Symbol: Cs
	Name of Element: Cesium
Atomic Weight:	Atomic Weight: 132.9054
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 8 · 1

Atomic Number:	Atomic Number: 58
Atomic Symbol:	Atomic Symbol: Ce
	Name of Element: Cerium
Atomic Weight:	Atomic Weight: 140.12
Electron Configuration:	Electron Configuration: 2 · 8 · 1820 · 8 · 2

Atomic Number:	Atomic Number: 6
Atomic Symbol:	Atomic Symbol: C
	Name of Element: Carbon
Atomic Weight:	Atomic Weight: 12.011
Electron Configuration:	Electron Configuration: 2 · 4

Atomic Number:	Atomic Number: 98
Atomic Symbol:	Atomic Symbol: Cf
	Name of Element: Californium
Atomic Weight:	Atomic Weight: (251)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 288 · 2

Atomic Number:	Atomic Number: 20
Atomic Symbol:	Atomic Symbol: Ca
	Name of Element: Calcium
Atomic Weight:	Atomic Weight: 40.08
Electron Configuration:	Electron Configuration: 2 · 8 · 8 · 2

Atomic Number:	Atomic Number: 48
Atomic Symbol:	Atomic Symbol: Cd
	Name of Element: Cadmium
Atomic Weight:	Atomic Weight: 112.41
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 2

Atomic Number:	Atomic Number: 35
Atomic Symbol:	Atomic Symbol: Br
	Name of Element: Bromine
Atomic Weight:	Atomic Weight: 79.904
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 7

Atomic Number:	Atomic Number: 5
Atomic Symbol:	Atomic Symbol: B
	Name of Element: Boron
Atomic Weight:	Atomic Weight: 10.81
Electron Configuration:	Electron Configuration: 2 · 3

Atomic Number:	Atomic Number: 107
Atomic Symbol:	Atomic Symbol: Bh
	Name of Element: Bohrium
Atomic Weight:	Atomic Weight: (262)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 3213 · 2

Atomic Number:	Atomic Number: 83
Atomic Symbol:	Atomic Symbol: Bi
	Name of Element: Bismuth
Atomic Weight:	Atomic Weight: 208.9804
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 5

Atomic Number:	Atomic Number: 4
Atomic Symbol:	Atomic Symbol: Be
	Name of Element: Beryllium
Atomic Weight:	Atomic Weight: 9.01218
Electron Configuration:	Electron Configuration: 2 · 2

Atomic Number:	Atomic Number: 97
Atomic Symbol:	Atomic Symbol: Bk
	Name of Element: Berkelium
Atomic Weight:	Atomic Weight: (247)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 278 · 2

Atomic Number:	Atomic Number: 56
Atomic Symbol:	Atomic Symbol: Ba
	Name of Element: Barium
Atomic Weight:	Atomic Weight: 137.33
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 8 · 2

Atomic Number:	Atomic Number: 85
Atomic Symbol:	Atomic Symbol: At
	Name of Element: Astatine
Atomic Weight:	Atomic Weight: (210)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 18 · 7

Atomic Number:	Atomic Number: 33
Atomic Symbol:	Atomic Symbol: As
	Name of Element: Arsenic
Atomic Weight:	Atomic Weight: 74.9216
Electron Configuration:	Electron Configuration: 2 · 8 · 18 · 5

Atomic Number:	Atomic Number: 18
Atomic Symbol:	Atomic Symbol: Ar
	Name of Element: Argon
Atomic Weight:	Atomic Weight: 39.948
Electron Configuration:	Electron Configuration: 2 · 8 · 8

Atomic Number:	Atomic Number: 51
Atomic Symbol:	Atomic Symbol: Sb
	Name of Element: Antimony
Atomic Weight:	Atomic Weight: 121.75
Electron Configuration:	Electron Configuration: 2 · 8 · 1818 · 5

Atomic Number:	Atomic Number: 95
Atomic Symbol:	Atomic Symbol: Am
	Name of Element: Americium
Atomic Weight:	Atomic Weight: (243)
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 258 · 2

Atomic Number:	Atomic Number: 13
Atomic Symbol:	Atomic Symbol: Al
	Name of Element: Aluminum
Atomic Weight:	Atomic Weight: 26.98154
Electron Configuration:	Electron Configuration: 2 · 8 · 3

Atomic Number:	Atomic Number: 89
Atomic Symbol:	Atomic Symbol: Ac
	Name of Element: Actinium
Atomic Weight:	Atomic Weight: 227.0278
Electron Configuration:	Electron Configuration: 2 · 8 · 1832 · 189 · 2

(showing atomic number and atomic symbol; click on atomic symbol for more detailed information)

Groups
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
1 H																	2 He
3 Li	4 Be											5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg											13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba	57-71 Lanthanide Series	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra	89-103 Actinide Series	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Uub	113 Uut	114 Uuq	115 Uup	116 Uuh		118 Uuo

Lanthanide Series
(Rare Earth Elements)

57 La

58 Ce

59 Pr

60 Nd

61 Pm

62 Sm

63 Eu

64 Gd

65 Tb

66 Dy

67 Ho

68 Er

69 Tm

70 Yb

71 Lu

Actinide Series
(Radioactive Rare Earth Elements)

89 Ac

90 Th

91 Pa

92 U

93 Np

94 Pu

95 Am

96 Cm

97 Bk

98 Cf

99 Es

100 Fm

101 Md

102 No

103 Lr

Organized array of all the chemical elements in approximately increasing order of their atomic weight. The elements show a periodic recurrence of certain properties, first discovered in 1869 by Dmitry I. Mendeleyev. Those in the same column (group) of the table as usually arranged have similar properties. In the 20th century, when the structure of atoms was understood, the table was seen to precisely reflect increasing order of atomic number. Members of the same group in the table have the same number of electrons in the outermost shells of their atoms and form bonds of the same type, usually with the same valence; the noble gases, with full outer shells, generally do not form bonds. The periodic table has thus greatly deepened understanding of bonding and chemical behaviour. It also allowed the prediction of new elements, many of which were later discovered or synthesized. For an illustration of the periodic table, see chemical element.

Learn more about periodic table with a free trial on Britannica.com.