,
, Periodic Table of Elements
Representative elements
Alkali Alkaline Halogens Noble
metals earth gases
metals
1 18
Period Group Group
number 1A 8A
2 13 14 15 16 17
1 2
Group Group Group Group Group Group
1 H 2A 3A 4A 5A 6A 7A
He
1.008 4.003
3 4 5 6 7 8 9 10
2 Li Be Transition elements B C N O F Ne
6.941 9.012 10.81 12.01 14.01 16.00 19.00 20.18
11 12 13 14 15 16 17 18
3 4 5 6 7 8 9 10 11 12
3 Na Mg 3B 4B 5B 6B 7B 8B 1B 2B
Al Si P S Cl Ar
22.99 24.31 26.98 28.09 30.97 32.07 35.45 39.95
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
39.10 40.08 44.96 47.87 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.41 69.72 72.64 74.92 78.96 79.90 83.80
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
85.47 87.62 88.91 91.22 92.91 95.94 (99) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3
55 56 57* 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
132.9 137.3 138.9 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)
87 88 89† 104 105 106 107 108 109 110 111 112 113 114 115 116 118
7 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn — — — — —
(223) (226) (227) (261) (262) (266) (264) (265) (266) (271) (272) (285) (284) (289) (288) (292) (294)
58 59 60 61 62 63 64 65 66 67 68 69 70 71
*Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
140.1 140.9 144.2 (145) 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0
90 91 92 93 94 95 96 97 98 99 100 101 102 103
†Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
232.0 231.0 238.0 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (262)
Metals Metalloids Nonmetals
, ATOMIC MASSES OF THE ELEMENTS
Name Symbol Atomic Number Atomic Massa Name Symbol Atomic Number Atomic Massa
Actinium Ac 89 (227)b Molybdenum Mo 42 95.94
Aluminum Al 13 26.98 Neodymium Nd 60 144.2
Americium Am 95 (243) Neon Ne 10 20.18
Antimony Sb 51 121.8 Neptunium Np 93 (237)
Argon Ar 18 39.95 Nickel Ni 28 58.69
Arsenic As 33 74.92 Niobium Nb 41 92.91
Astatine At 85 (210) Nitrogen N 7 14.01
Barium Ba 56 137.3 Nobelium No 102 (259)
Berkelium Bk 97 (247) Osmium Os 76 190.2
Beryllium Be 4 9.012 Oxygen O 8 16.00
Bismuth Bi 83 209.0 Palladium Pd 46 106.4
Bohrium Bh 107 (264) Phosphorus P 15 30.97
Boron B 5 10.81 Platinum Pt 78 195.1
Bromine Br 35 79.90 Plutonium Pu 94 (244)
Cadmium Cd 48 112.4 Polonium Po 84 (209)
Calcium Ca 20 40.08 Potassium K 19 39.10
Californium Cf 98 (251) Praseodymium Pr 59 140.9
Carbon C 6 12.01 Promethium Pm 61 (145)
Cerium Ce 58 140.1 Protactinium Pa 91 231.0
Cesium Cs 55 132.9 Radium Ra 88 (226)
Chlorine Cl 17 35.45 Radon Rn 86 (222)
Chromium Cr 24 52.00 Rhenium Re 75 186.2
Cobalt Co 27 58.93 Rhodium Rh 45 102.9
Copernicium Cn 112 (285) Roentgenium Rg 111 (272)
Copper Cu 29 63.55 Rubidium Rb 37 85.47
Curium Cm 96 (247) Ruthenium Ru 44 101.1
Darmstadtium Ds 110 (271) Rutherfordium Rf 104 (261)
Dubnium Db 105 (262) Samarium Sm 62 150.4
Dysprosium Dy 66 162.5 Scandium Sc 21 44.96
Einsteinium Es 99 (252) Seaborgium Sg 106 (266)
Erbium Er 68 167.3 Selenium Se 34 78.96
Europium Eu 63 152.0 Silicon Si 14 28.09
Fermium Fm 100 (257) Silver Ag 47 107.9
Fluorine F 9 19.00 Sodium Na 11 22.99
Francium Fr 87 (223) Strontium Sr 38 87.62
Gadolinium Gd 64 157.3 Sulfur S 16 32.07
Gallium Ga 31 69.72 Tantalum Ta 73 180.9
Germanium Ge 32 72.64 Technetium Tc 43 (99)
Gold Au 79 197.0 Tellurium Te 52 127.6
Hafnium Hf 72 178.5 Terbium Tb 65 158.9
Hassium Hs 108 (265) Thallium Tl 81 204.4
Helium He 2 4.003 Thorium Th 90 232.0
Holmium Ho 67 164.9 Thulium Tm 69 168.9
Hydrogen H 1 1.008 Tin Sn 50 118.7
Indium In 49 114.8 Titanium Ti 22 47.87
Iodine I 53 126.9 Tungsten W 74 183.8
Iridium Ir 77 192.2 Uranium U 92 238.0
Iron Fe 26 55.85 Vanadium V 23 50.94
Krypton Kr 36 83.80 Xenon Xe 54 131.3
Lanthanum La 57 138.9 Ytterbium Yb 70 173.0
Lawrencium Lr 103 (262) Yttrium Y 39 88.91
Lead Pb 82 207.2 Zinc Zn 30 65.41
Lithium Li 3 6.941 Zirconium Zr 40 91.22
Lutetium Lu 71 175.0 — — 113 (284)
Magnesium Mg 12 24.31 — — 114 (289)
Manganese Mn 25 54.94 — — 115 (288)
Meitnerium Mt 109 (268) — — 116 (292)
Mendelevium Md 101 (258) — — 118 (294)
Mercury Hg 80 200.6
a
Values for atomic masses are given to four significant figures.
b
Values in parentheses are the mass number of an important radioactive isotope.
, Periodic Table of Elements
Representative elements
Alkali Alkaline Halogens Noble
metals earth gases
metals
1 18
Period Group Group
number 1A 8A
2 13 14 15 16 17
1 2
Group Group Group Group Group Group
1 H 2A 3A 4A 5A 6A 7A
He
1.008 4.003
3 4 5 6 7 8 9 10
2 Li Be Transition elements B C N O F Ne
6.941 9.012 10.81 12.01 14.01 16.00 19.00 20.18
11 12 13 14 15 16 17 18
3 4 5 6 7 8 9 10 11 12
3 Na Mg 3B 4B 5B 6B 7B 8B 1B 2B
Al Si P S Cl Ar
22.99 24.31 26.98 28.09 30.97 32.07 35.45 39.95
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
39.10 40.08 44.96 47.87 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.41 69.72 72.64 74.92 78.96 79.90 83.80
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
85.47 87.62 88.91 91.22 92.91 95.94 (99) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3
55 56 57* 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
132.9 137.3 138.9 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)
87 88 89† 104 105 106 107 108 109 110 111 112 113 114 115 116 118
7 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn — — — — —
(223) (226) (227) (261) (262) (266) (264) (265) (266) (271) (272) (285) (284) (289) (288) (292) (294)
58 59 60 61 62 63 64 65 66 67 68 69 70 71
*Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
140.1 140.9 144.2 (145) 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.0 175.0
90 91 92 93 94 95 96 97 98 99 100 101 102 103
†Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
232.0 231.0 238.0 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (262)
Metals Metalloids Nonmetals
, ATOMIC MASSES OF THE ELEMENTS
Name Symbol Atomic Number Atomic Massa Name Symbol Atomic Number Atomic Massa
Actinium Ac 89 (227)b Molybdenum Mo 42 95.94
Aluminum Al 13 26.98 Neodymium Nd 60 144.2
Americium Am 95 (243) Neon Ne 10 20.18
Antimony Sb 51 121.8 Neptunium Np 93 (237)
Argon Ar 18 39.95 Nickel Ni 28 58.69
Arsenic As 33 74.92 Niobium Nb 41 92.91
Astatine At 85 (210) Nitrogen N 7 14.01
Barium Ba 56 137.3 Nobelium No 102 (259)
Berkelium Bk 97 (247) Osmium Os 76 190.2
Beryllium Be 4 9.012 Oxygen O 8 16.00
Bismuth Bi 83 209.0 Palladium Pd 46 106.4
Bohrium Bh 107 (264) Phosphorus P 15 30.97
Boron B 5 10.81 Platinum Pt 78 195.1
Bromine Br 35 79.90 Plutonium Pu 94 (244)
Cadmium Cd 48 112.4 Polonium Po 84 (209)
Calcium Ca 20 40.08 Potassium K 19 39.10
Californium Cf 98 (251) Praseodymium Pr 59 140.9
Carbon C 6 12.01 Promethium Pm 61 (145)
Cerium Ce 58 140.1 Protactinium Pa 91 231.0
Cesium Cs 55 132.9 Radium Ra 88 (226)
Chlorine Cl 17 35.45 Radon Rn 86 (222)
Chromium Cr 24 52.00 Rhenium Re 75 186.2
Cobalt Co 27 58.93 Rhodium Rh 45 102.9
Copernicium Cn 112 (285) Roentgenium Rg 111 (272)
Copper Cu 29 63.55 Rubidium Rb 37 85.47
Curium Cm 96 (247) Ruthenium Ru 44 101.1
Darmstadtium Ds 110 (271) Rutherfordium Rf 104 (261)
Dubnium Db 105 (262) Samarium Sm 62 150.4
Dysprosium Dy 66 162.5 Scandium Sc 21 44.96
Einsteinium Es 99 (252) Seaborgium Sg 106 (266)
Erbium Er 68 167.3 Selenium Se 34 78.96
Europium Eu 63 152.0 Silicon Si 14 28.09
Fermium Fm 100 (257) Silver Ag 47 107.9
Fluorine F 9 19.00 Sodium Na 11 22.99
Francium Fr 87 (223) Strontium Sr 38 87.62
Gadolinium Gd 64 157.3 Sulfur S 16 32.07
Gallium Ga 31 69.72 Tantalum Ta 73 180.9
Germanium Ge 32 72.64 Technetium Tc 43 (99)
Gold Au 79 197.0 Tellurium Te 52 127.6
Hafnium Hf 72 178.5 Terbium Tb 65 158.9
Hassium Hs 108 (265) Thallium Tl 81 204.4
Helium He 2 4.003 Thorium Th 90 232.0
Holmium Ho 67 164.9 Thulium Tm 69 168.9
Hydrogen H 1 1.008 Tin Sn 50 118.7
Indium In 49 114.8 Titanium Ti 22 47.87
Iodine I 53 126.9 Tungsten W 74 183.8
Iridium Ir 77 192.2 Uranium U 92 238.0
Iron Fe 26 55.85 Vanadium V 23 50.94
Krypton Kr 36 83.80 Xenon Xe 54 131.3
Lanthanum La 57 138.9 Ytterbium Yb 70 173.0
Lawrencium Lr 103 (262) Yttrium Y 39 88.91
Lead Pb 82 207.2 Zinc Zn 30 65.41
Lithium Li 3 6.941 Zirconium Zr 40 91.22
Lutetium Lu 71 175.0 — — 113 (284)
Magnesium Mg 12 24.31 — — 114 (289)
Manganese Mn 25 54.94 — — 115 (288)
Meitnerium Mt 109 (268) — — 116 (292)
Mendelevium Md 101 (258) — — 118 (294)
Mercury Hg 80 200.6
a
Values for atomic masses are given to four significant figures.
b
Values in parentheses are the mass number of an important radioactive isotope.
