Mass Number
The mass number (A) of an atom is the number of protons and neutrons it has in its nucleus; e.g., A = 35 for a chlorine atom which contains 18 neutrons (35Cl), and A = 37 for one which contains 20 neutrons (37Cl).
In nuclide symbols the mass number is given as a leading superscript.
In isotope names (e. g. carbon-14, sodium-23) the mass number is the number following the element name.
Click on an item to paste into clipboard or use clipboard symbol at end to clipboard all values
paste all data into clipboard
| Beryllium | 9 | Clip | |
| Carbon | 12 | Clip | |
| Deuterium | 2 | Clip | |
| Helium | 4 | Clip | |
| Nitrogen | 14 | Clip | |
| Oxygen | 16 | Clip | |
| Tritium | 3 | Clip |
paste all data into clipboardSee also: Atomic Mass Unit, Atomic Number, Nuclide Symbol, Proton.
Subjects: Physics