atomic number
Element's proton tally
The atomic number of a chemical element is the number of protons in its nucleus, which determines the element's identity and position in the periodic table.
Hydrogen has atomic number 1, helium 2, carbon 6.
Unlike atomic weight, the atomic number is always a whole number.
Elements are arranged by atomic number, not alphabetically.
proton
Positive nuclear particle
isotope · element · periodic table · valence · orbital · shell · energy level · nuclide · stable · radioactive
- math & science termspi, infinity, zero, billion, million
- periodic tableperiodic table, elements, hydrogen, helium, carbon
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nuclear property type
atomic numberatomic mass
Weighted average of isotopes
mass number · atomic weight · molecular weight · molar mass · atomic mass unit
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