Electronic configuration
electronic configurationThe order electrons are arranged in different shells., electronic structure and electronic arrangement all mean the same thing.
electronSubatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. orbit the nucleusThe central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. The plural of nucleus is nuclei. in shells.
- each shell is at a different distance from the nucleus. The first shell is nearest to the nucleus.
- different shells hold a different maximum number of electrons.
- the electrons fill the lowest available shell first 鈥 the one nearest the nucleus.
- when this shell is full, the electrons begin to fill the next shell.
The table below shows the maximum number of electrons each shell can hold for elements with atomic numbers 1 to 20.
| Shell | Maximum |
| First | 2 |
| Second | 8 |
| Third | 8 |
| Fourth | 2 |
| Shell | First |
|---|---|
| Maximum | 2 |
| Shell | Second |
|---|---|
| Maximum | 8 |
| Shell | Third |
|---|---|
| Maximum | 8 |
| Shell | Fourth |
|---|---|
| Maximum | 2 |