- Structure of the atom
- Isotopes - Atoms of the same element with different numbers of neutrons.
- Atoms have the same number of protons and electrons
- Nucleus is very small compared with the overal size of the atom
- Atoms have electrons in shells
- No. of protons determines which element the atom is part of
- Protons are positive; electrons are negative
- Protons and electrons balance each other out so the atom is neutral