# Atomic Mass and Avogadro Number

by Dasa . 27 No 2021

The ‘mol’ is the SI (International System of Units) base unit for the amount of substance. A ‘mol’ contains 6.02214076×10²³ elementary entities, which may be atoms, molecules, ions, or electrons. The number 6.02214076×10²³ is called Avogadro’s Number.

1 mol = 6.02214076×10²³ elements.

The below table shows the details of protons, neutrons, electrons, mass number, and atomic mass for various elements in the Periodic Table.

Protons and neutrons have mass. But electrons do not have mass. So when you add up the number of protons & neutrons, we get the Mass Number. The last column of the table shows the atomic mass in gram/mol.

## Isotopes:

Atomic mass & mass numbers should be the same. But, Some elements will have different quantities of the neutron in nature. So Atomic mass indicates the average of masses. These elements that differ in their number of neutrons are called Isotops.

For example,
Most Carbon in the earth will have six neutrons, but 1.1% of the carbon present has seven neutrons.

As per the table,

1 mol of H = 1 proton
= 1.0080 grams
That means,

1 mol of any element contains 6.02214076×10²³ elements.
6.02214076×10²³ elements of H = 1.0080 grams

1 element of H = $\dfrac{1.0080}{6.02214076 * 10^{23}}$ grams/element

= $1.6738 * 10^{-24}$ grams/element

Atomic Number Symbol Name Protons Neutrons Electrons Mass Number Atomic Mass (g/mol)
1 H Hydrogen 1 0 1 1 1.0080
2 He Helium 2 2 2 4 4.0026
3 Li Lithium 3 4 3 7 7.0000
4 Be Beryllium 4 5 4 9 9.0122
5 B Boron 5 6 5 11 10.8100
6 C Carbon 6 6 6 12 12.0110
7 N Nitrogen 7 7 7 14 14.0070
8 O Oxygen 8 8 8 16 15.9990
9 F Fluorine 9 10 9 19 18.9984
10 Ne Neon 10 10 10 20 20.1800
11 Na Sodium 11 12 11 23 22.9898
12 Mg Magnesium 12 12 12 24 24.3050
13 Al Aluminum 13 14 13 27 26.9815
14 Si Silicon 14 14 14 28 28.0850
15 P Phosphorus 15 16 15 31 30.9738
16 S Sulfur 16 16 16 32 32.0700
17 Cl Chlorine 17 18 17 35 35.4500
18 Ar Argon 18 22 18 40 39.9000
19 K Potassium 19 20 19 39 39.0983
20 Ca Calcium 20 20 20 40 40.0800
21 Sc Scandium 21 24 21 45 44.9559
22 Ti Titanium 22 26 22 48 47.8670
23 V Vanadium 23 28 23 51 50.9415
24 Cr Chromium 24 28 24 52 51.9960
25 Mn Manganese 25 30 25 55 54.9380
26 Fe Iron 26 30 26 56 55.8400
27 Co Cobalt 27 32 27 59 58.9332
28 Ni Nickel 28 30 28 58 58.6930
29 Cu Copper 29 36 29 65 63.5500
30 Zn Zinc 30 35 30 65 65.4000
31 Ga Gallium 31 38 31 69 69.7230
32 Ge Germanium 32 41 32 73 72.6300
33 As Arsenic 33 42 33 75 74.9216
34 Se Selenium 34 45 34 79 78.9700
35 Br Bromine 35 46 35 81 79.9000
36 Kr Krypton 36 50 36 86 83.8000
37 Rb Rubidium 37 48 37 85 85.4680
38 Sr Strontium 38 50 38 88 87.6200
39 Y Yttrium 39 50 39 89 88.9058
40 Zr Zirconium 40 52 40 92 91.2200
41 Nb Niobium 41 52 41 93 92.9064
42 Mo Molybdenum 42 54 42 96 95.9500
43 Tc Technetium 43 54 43 97 96.9064
44 Ru Ruthenium 44 57 44 101 101.1000
45 Rh Rhodium 45 58 45 103 102.9055
46 Pd Palladium 46 60 46 106 106.4200
47 Ag Silver 47 61 47 108 107.8680
48 Cd Cadmium 48 64 48 112 112.4100
49 In Indium 49 66 49 115 114.8180
50 Sn Tin 50 69 50 119 118.7100
51 Sb Antimony 51 71 51 122 121.7600
52 Te Tellurium 52 76 52 128 127.6000
53 I Iodine 53 74 53 127 126.9045
54 Xe Xenon 54 77 54 131 131.2900
55 Cs Cesium 55 78 55 133 132.9055
56 Ba Barium 56 81 56 137 137.3300
57 La Lanthanum 57 82 57 139 138.9055
58 Ce Cerium 58 82 58 140 140.1160
59 Pr Praseodymium 59 82 59 141 140.9077
60 Nd Neodymium 60 84 60 144 144.2400
61 Pm Promethium 61 84 61 145 144.9128
62 Sm Samarium 62 88 62 150 150.4000
63 Eu Europium 63 89 63 152 151.9640
64 Gd Gadolinium 64 93 64 157 157.2000
65 Tb Terbium 65 94 65 159 158.9254
66 Dy Dysprosium 66 97 66 163 162.5000
67 Ho Holmium 67 98 67 165 164.9303
68 Er Erbium 68 99 68 167 167.2600
69 Tm Thulium 69 100 69 169 168.9342
70 Yb Ytterbium 70 103 70 173 173.0500
71 Lu Lutetium 71 104 71 175 174.9668
72 Hf Hafnium 72 106 72 178 178.4900
73 Ta Tantalum 73 108 73 181 180.9479
74 W Tungsten 74 110 74 184 183.8400
75 Re Rhenium 75 111 75 186 186.2070
76 Os Osmium 76 114 76 190 190.2000
77 Ir Iridium 77 115 77 192 192.2200
78 Pt Platinum 78 117 78 195 195.0800
79 Au Gold 79 118 79 197 196.9666
80 Hg Mercury 80 121 80 201 200.5900
81 Tl Thallium 81 123 81 204 204.3830
82 Pb Lead 82 125 82 207 207.0000
83 Bi Bismuth 83 126 83 209 208.9804
84 Po Polonium 84 125 84 209 208.9824
85 At Astatine 85 125 85 210 209.9872
86 Rn Radon 86 136 86 222 222.0176
87 Fr Francium 87 136 87 223 223.0197
88 Ra Radium 88 138 88 226 226.0254
89 Ac Actinium 89 138 89 227 227.0278
90 Th Thorium 90 142 90 232 232.0380
91 Pa Protactinium 91 140 91 231 231.0359
92 U Uranium 92 146 92 238 238.0289
93 Np Neptunium 93 144 93 237 237.0482
94 Pu Plutonium 94 150 94 244 244.0642
95 Am Americium 95 148 95 243 243.0614
96 Cm Curium 96 151 96 247 247.0704
97 Bk Berkelium 97 150 97 247 247.0703
98 Cf Californium 98 153 98 251 251.0796
99 Es Einsteinium 99 153 99 252 252.0830
100 Fm Fermium 100 157 100 257 257.0951
101 Md Mendelevium 101 157 101 258 258.0984
102 No Nobelium 102 157 102 259 259.1010
103 Lr Lawrencium 103 163 103 266 266.1200
104 Rf Rutherfordium 104 163 104 267 267.1220
105 Db Dubnium 105 163 105 268 268.1260
106 Sg Seaborgium 106 163 106 269 269.1280
107 Bh Bohrium 107 163 107 270 270.1330
108 Hs Hassium 108 161 108 269 269.1336
109 Mt Meitnerium 109 168 109 277 277.1540
110 Ds Darmstadtium 110 172 110 282 282.1660
111 Rg Roentgenium 111 171 111 282 282.1690
112 Cn Copernicium 112 174 112 286 286.1790
113 Nh Nihonium 113 173 113 286 286.1820
114 Fl Flerovium 114 176 114 290 290.1920
115 Mc Moscovium 115 175 115 290 290.1960
116 Lv Livermorium 116 177 116 293 293.2050
117 Ts Tennessine 117 177 117 294 294.2110
118 Og Oganesson 118 176 118 295 295.2160

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