Each energy level (or electron shell) in an atom can hold a maximum number of electrons given by the formula 2n22n^22n2, where nnn is the principal quantum number (the energy level number).
- The 1st energy level (n=1) can hold up to 2 electrons.
- The 2nd energy level (n=2) can hold up to 8 electrons.
- The 3rd energy level (n=3) can hold up to 18 electrons.
- The 4th energy level (n=4) can hold up to 32 electrons.
This pattern continues for higher levels, increasing as 2n22n^22n2 electrons per level.
The electrons are arranged in orbitals within these levels, with each orbital holding 2 electrons. The sublevels (s, p, d, f) have different numbers of orbitals, which together sum to the total capacity per energy level. Thus, the number of electrons per level is:
- Level 1: 2 electrons
- Level 2: 8 electrons
- Level 3: 18 electrons
- Level 4: 32 electrons
This matches the quantum mechanical model of the atom and the organization of electrons in shells.
