What is the atomic weight of an element?

Answer 1

Helium is a non meta element. Atomic Mass of it is 4.

Answer 2

See the Web Links to the left for other sources.

(atomic number, symbol, name, atomic weight)

1 H Hydrogen 1.00794(7)
2 He Helium 4.002602(2)
3 Li Lithium 6.941(2)
4 Be Beryllium 9.012182(3)
5 B Boron 10.811(7)
6 C Carbon 12.0107(8)
7 N Nitrogen 14.0067(2)
8 O Oxygen 15.9994(3)
9 F Fluorine 18.9984032(5)
10 Ne Neon 20.1797(6)
11 Na Sodium 22.98976928(2)
12 Mg Magnesium 24.3050(6)
13 Al Aluminium 26.9815386(8)
14 Si Silicon 28.0855(3)
15 P Phosphorus 30.973762(2)
16 S Sulfur 32.065(5)
17 Cl Chlorine 35.453(2)
18 Ar Argon 39.948(1)
19 K Potassium 39.0983(1)
20 Ca Calcium 40.078(4)
21 Sc Scandium 44.955912(6)
22 Ti Titanium 47.867(1)
23 V Vanadium 50.9415(1)
24 Cr Chromium 51.9961(6)
25 Mn Manganese 54.938045(5)
26 Fe Iron 55.845(2)
27 Co Cobalt 58.933195(5)
28 Ni Nickel 58.6934(2)
29 Cu Copper 63.546(3)
30 Zn Zinc 65.409(4)
31 Ga Gallium 69.723(1)
32 Ge Germanium 72.64(1)
33 As Arsenic 74.92160(2)
34 Se Selenium 78.96(3)
35 Br Bromine 79.904(1)
36 Kr Krypton 83.798(2)
37 Rb Rubidium 85.4678(3)
38 Sr Strontium 87.62(1)
39 Y Yttrium 88.90585(2)
40 Zr Zirconium 91.224(2)
41 Nb Niobium 92.90638(2)
42 Mo Molybdenum 95.94(2)
43 Tc Technetium [98]
44 Ru Ruthenium 101.07(2)
45 Rh Rhodium 102.90550(2)
46 Pd Palladium 106.42(1)
47 Ag Silver 107.8682(2)
48 Cd Cadmium 112.411(8)
49 In Indium 114.818(3)
50 Sn Tin 118.710(7)
51 Sb Antimony 121.760(1)
52 Te Tellurium 127.60(3)
53 I Iodine 126.90447(3)
54 Xe Xenon 131.293(6)
55 Cs Caesium 132.9054519(2)
56 Ba Barium 137.327(7)
57 La Lanthanum 138.90547(7)
58 Ce Cerium 140.116(1)
59 Pr Praseodymium 140.90765(2)
60 Nd Neodymium 144.242(3)
61 Pm Promethium [145] 5
62 Sm Samarium 150.36(2)
63 Eu Europium 151.964(1)
64 Gd Gadolinium 157.25(3)
65 Tb Terbium 158.92535(2)
66 Dy Dysprosium 162.500(1)
67 Ho Holmium 164.93032(2)
68 Er Erbium 167.259(3)
69 Tm Thulium 168.93421(2)
70 Yb Ytterbium 173.04(3)
71 Lu Lutetium 174.967(1)
72 Hf Hafnium 178.49(2)
73 Ta Tantalum 180.94788(2)
74 W Tungsten 183.84(1)
75 Re Rhenium 186.207(1)
76 Os Osmium 190.23(3)
77 Ir Iridium 192.217(3)
78 Pt Platinum 195.084(9)
79 Au Gold 196.966569(4)
80 Hg Mercury 200.59(2)
81 Tl Thallium 204.3833(2)
82 Pb Lead 207.2(1)
83 Bi Bismuth 208.98040(1)
84 Po Polonium [209]
85 At Astatine [210]
86 Rn Radon [222] 5
87 Fr Francium [223]
88 Ra Radium [226] 5
89 Ac Actinium [227]
90 Th Thorium 232.03806(2)
91 Pa Protactinium 231.03588(2)
92 U Uranium 238.02891(3)
93 Np Neptunium [237]
94 Pu Plutonium [244]
95 Am Americium [243]
96 Cm Curium [247]
97 Bk Berkelium [247]
98 Cf Californium [251]
99 Es Einsteinium [252]
100 Fm Fermium [257]
101 Md Mendelevium [258]
102 No Nobelium [259]
103 Lr Lawrencium [262]
104 Rf Rutherfordium [267]
105 Db Dubnium [268]
106 Sg Seaborgium [271]
107 Bh Bohrium [272]
108 Hs Hassium [270]
109 Mt Meitnerium [276]
110 Ds Darmstadtium [281]
111 Rg Roentgenium [280]
112 Uub Ununbium [285]
113 Uut Ununtrium [284]
114 Uuq Ununquadium [289]
115 Uup Ununpentium [288]
116 Uuh Ununhexium [293]
118 Uuo Ununoctium [294]

Answer 3

No Symbol Name Atomic Wt 1 H Hydrogen 1.00794(7) 2 He Helium 4.002602(2) 3 Li Lithium [6.941(2)] 4 Be Beryllium 9.012182(3) 5 B Boron 10.811(7)

6 C Carbon 12.0107(8)

7 N Nitrogen 14.0067(2)

8 O Oxygen 15.9994(3)

9 F Fluorine 18.9984032(5) 10 Ne Neon 20.1797(6)

11 Na Sodium 22.98976928(2) 12 Mg Magnesium 24.3050(6) 13 Al Aluminium 26.9815386(8) 14 Si Silicon 28.0855(3)

15 P Phosphorus 30.973762(2) 16 S Sulfur 32.065(5)

17 Cl Chlorine 35.453(2)

18 Ar Argon 39.948(1)

19 K Potassium 39.0983(1)

20 Ca Calcium 40.078(4)

21 Sc Scandium 44.955912(6) 22 Ti Titanium 47.867(1) 23 V Vanadium 50.9415(1) 24 Cr Chromium 51.9961(6) 25 Mn Manganese 54.938045(5) 26 Fe Iron 55.845(2) 27 Co Cobalt 58.933195(5) 28 Ni Nickel 58.6934(4) 29 Cu Copper 63.546(3)

30 Zn Zinc 65.38(2)

31 Ga Gallium 69.723(1) 32 Ge Germanium 72.64(1) 33 As Arsenic 74.92160(2) 34 Se Selenium 78.96(3) 35 Br Bromine 79.904(1) 36 Kr Krypton 83.798(2)

37 Rb Rubidium 85.4678(3)

38 Sr Strontium 87.62(1)

39 Y Yttrium 88.90585(2) 40 Zr Zirconium 91.224(2)

41 Nb Niobium 92.90638(2) 42 Mo Molybdenum 95.96(2)

43 Tc Technetium [98]

44 Ru Ruthenium 101.07(2)

45 Rh Rhodium 102.90550(2) 46 Pd Palladium 106.42(1)

47 Ag Silver 107.8682(2)

48 Cd Cadmium 112.411(8)

49 In Indium 114.818(3) 50 Sn Tin 118.710(7)

51 Sb Antimony 121.760(1)

52 Te Tellurium 127.60(3)

53 I Iodine 126.90447(3) 54 Xe Xenon 131.293(6)

55 Cs Caesium 132.9054519(2) 56 Ba Barium 137.327(7) 57 La Lanthanum 138.90547(7)

58 Ce Cerium 140.116(1)

59 Pr Praseodymium 140.90765(2) 60 Nd Neodymium 144.242(3)

61 Pm Promethium [145]

62 Sm Samarium 150.36(2)

63 Eu Europium 151.964(1)

64 Gd Gadolinium 157.25(3)

65 Tb Terbium 158.92535(2) 66 Dy Dysprosium 162.500(1)

67 Ho Holmium 164.93032(2) 68 Er Erbium 167.259(3)

69 Tm Thulium 168.93421(2) 70 Yb Ytterbium 173.054(5)

71 Lu Lutetium 174.9668(1)

72 Hf Hafnium 178.49(2) 73 Ta Tantalum 180.94788(2) 74 W Tungsten 183.84(1) 75 Re Rhenium 186.207(1) 76 Os Osmium 190.23(3)

77 Ir Iridium 192.217(3) 78 Pt Platinum 195.084(9) 79 Au Gold 196.966569(4) 80 Hg Mercury 200.59(2) 81 Tl Thallium 204.3833(2) 82 Pb Lead 207.2(1)

83 Bi Bismuth 208.98040(1) 84 Po Polonium [209]

85 At Astatine [210]

86 Rn Radon [222]

87 Fr Francium [223]

88 Ra Radium [226]

89 Ac Actinium [227]

90 Th Thorium 232.03806(2)

91 Pa Protactinium 231.03588(2)

92 U Uranium 238.02891(3)

93 Np Neptunium [237]

94 Pu Plutonium [244]

95 Am Americium [243]

96 Cm Curium [247]

97 Bk Berkelium [247]

98 Cf Californium [251]

99 Es Einsteinium [252]

100 Fm Fermium [257]

101 Md Mendelevium [258]

102 No Nobelium [259]

103 Lr Lawrencium [262]

104 Rf Rutherfordium [267]

105 Db Dubnium [268]

106 Sg Seaborgium [271]

107 Bh Bohrium [272]

108 Hs Hassium [270]

109 Mt Meitnerium [276]

110 Ds Darmstadtium [281]

111 Rg Roentgenium [280]

112 Uub Ununbium [285]

113 Uut Ununtrium [284]

114 Uuq Ununquadium [289]

115 Uup Ununpentium [288]

116 Uuh Ununhexium [293]

118 Uuo Ununoctium [294]

[number] is estimated

(number) is rounded

Answer 4

Why are atomic weights given as fraction and not whole numbes like weight = proton + neutrons? Because they are taking an average of the weight of the naturally occurring isotopes, so that when you use the tables and you are using atoms from earth (most do :D ) then these fraction values will be correct most of the time, whereas just taking the weight of the most common isotope and ignore the others would give major errors.

Answer 5

The atomic weight of an element is the average mass of an atom of that element, taking into account the abundance of each isotope. It is expressed in Atomic Mass units (amu) and can be found on the Periodic Table.

Answer 6

To find this out you need to look at a periodic table. The link below will show you one.

Answer 7

the atomic weight of an element is the