The mass number of an element is the sum of the number of protons and neutrons in its atomic nucleus. Here are the mass numbers of the first 100 elements:
- Hydrogen (H): 1
- Helium (He): 4
- Lithium (Li): 7
- Beryllium (Be): 9
- Boron (B): 11
- Carbon (C): 12
- Nitrogen (N): 14
- Oxygen (O): 16
- Fluorine (F): 19
- Neon (Ne): 20
- Sodium (Na): 23
- Magnesium (Mg): 24
- Aluminum (Al): 27
- Silicon (Si): 28
- Phosphorus (P): 31
- Sulfur (S): 32
- Chlorine (Cl): 35.5
- Argon (Ar): 40
- Potassium (K): 39
- Calcium (Ca): 40
- Scandium (Sc): 45
- Titanium (Ti): 48
- Vanadium (V): 51
- Chromium (Cr): 52
- Manganese (Mn): 55
- Iron (Fe): 56
- Cobalt (Co): 59
- Nickel (Ni): 59
- Copper (Cu): 63.5
- Zinc (Zn): 65
- Gallium (Ga): 70
- Germanium (Ge): 73
- Arsenic (As): 75
- Selenium (Se): 79
- Bromine (Br): 80
- Krypton (Kr): 84
- Rubidium (Rb): 85
- Strontium (Sr): 88
- Yttrium (Y): 89
- Zirconium (Zr): 91
- Niobium (Nb): 93
- Molybdenum (Mo): 96
- Technetium (Tc): 98
- Ruthenium (Ru): 101
- Rhodium (Rh): 103
- Palladium (Pd): 106
- Silver (Ag): 108
- Cadmium (Cd): 112
- Indium (In): 115
- Tin (Sn): 119
- Antimony (Sb): 122
- Tellurium (Te