How many electrons fit
A shell cannot hold an unlimited number of electrons. Each energy level has a maximum, and it is fixed.
| Energy level | Maximum number of electrons |
|---|---|
| 1 (K) | 2 |
| 2 (L) | 8 |
| 3 (M) | 18 |
| 4 (N) | 32 |
Table 3.1 — the maximum each of the first four energy levels can hold.
The numbers grow quickly: 2, then 8, then 18, then 32. Each level further out has room for far more than the one inside it, which fits what you already know — the shells are larger the further from the nucleus they are.
Worth committing to memory
2, 8, 18, 32. Everything in the next section is built on these four numbers, and the first two do nearly all the work for the twenty elements you will study.
Try this
With your teacher's guidance, choose suitable materials and build models of atoms that show their three-dimensional shape. Display what you make in the classroom.