The mass number of an atom represents the total number of protons and neutrons in its nucleus. Here are the mass numbers of the first 30 elements without decimals:
- Hydrogen (H): Mass number = 1
- Helium (He): Mass number = 4
- Lithium (Li): Mass number = 7
- Beryllium (Be): Mass number = 9
- Boron (B): Mass number = 11
- Carbon (C): Mass number = 12
- Nitrogen (N): Mass number = 14
- Oxygen (O): Mass number = 16
- Fluorine (F): Mass number = 19
- Neon (Ne): Mass number = 20
- Sodium (Na): Mass number = 23
- Magnesium (Mg): Mass number = 24
- Aluminum (Al): Mass number = 27
- Silicon (Si): Mass number = 28
- Phosphorus (P): Mass number = 31
- Sulfur (S): Mass number = 32
- Chlorine (Cl): Mass number = 35
- Argon (Ar): Mass number = 40
- Potassium (K): Mass number = 39
- Calcium (Ca): Mass number = 40
- Scandium (Sc): Mass number = 45
- Titanium (Ti): Mass number = 48
- Vanadium (V): Mass number = 51
- Chromium (Cr): Mass number = 52
- Manganese (Mn): Mass number = 55
- Iron (Fe): Mass number = 56
- Cobalt (Co): Mass number = 59
- Nickel (Ni): Mass number = 58
- Copper (Cu): Mass number = 63
- Zinc (Zn): Mass number = 65
These mass numbers represent the sum of protons and neutrons in the nucleus of each element, providing an estimate of the atomic mass. Note that the atomic mass may vary slightly due to the presence of different isotopes with different abundances.