Explanation:
1. Electrons surround the nucleus in defined regions called orbits.
2. The shells further away from the nucleus are larger and can hold more electrons.
3. The shells closer to the nucleus are smaller and can hold less electrons.
4. The closest shell (closest to the nucleus) can hold a maximum of two electrons.
5. Once the first shell is full, the second shell begins to fill. It can hold a maximum of eight electrons.
6. Once the second shell is full, the third shell begins to fill.
7. Once the third shell contains Eighteen electrons, the fourth shell begins to fill.
8. The arrangement of electrons in shells around the nucleus is referred to as an atom's electronic configuration.
