Electronic arrangement
1. Electrons are layered on different electron layers that are close to and far from the nucleus and whose energy is from low to high.
2. The maximum number of electrons contained in each layer is 2n2 (n represents the number of electronic layers).
3. The number of outermost electrons does not exceed 8 (the first layer does not exceed 2), the secondary outer layer does not exceed 18, and the third last layer does not exceed 32.
4, the electrons are always ranked first in the lowest energy electronic layer, that is, the first layer is first, when the first layer is full, then the second layer, after the second layer is full, and then the third layer.