# Atomic number and mass number

> Atomic number = number of protons (= electrons in a neutral atom); mass number = protons + neutrons.

> [ar-EG] الـ Atomic number = عدد الـ protons (وهو نفسه عدد الـ electrons في الذرة المتعادلة)؛ والـ mass number = protons + neutrons.

Part of: Transition Elements (https://yaani.ai/en/learn/chemistry/chem-s3-en.ch1)

## Builds on

- Structure of the atom
- The four arithmetic operations


Source: https://yaani.ai/en/concept/atom.atomic-mass-number