Electron Configuration
Sub-Shell and Maximum Electron
| Sub-Shell |
Maximum Electron |
| s |
2 |
| p |
6 |
| d |
10 |
| f |
14 |
How to Read / Order
- Start from the top-most arrow
- Follow the direction of the arrow. For example;
- 1s, 2s, 2p, 3s
- Exponent the electron with maximum number of sub-shell until the total of exponents is equals to
Atom Number.
- If the total is more than Atom Number, subtract the the last electron's exponent to make the total
equals to the atom number.
Examples
1s2, 2s2, 2p6, 3s2
1s2, 2s2, 2p6, 3s2, 3p6,
4s2, 3d10, 4p3
Electron Configuration Based on Shell
an atom figure with shell labels (Oxygen)
Electron Count Rules
| Shell K |
Write 2 if electron ≥ 2 |
| Write 1 if electron < 2 (only for Hydrogen) |
| Shell L |
Write 8 if electron ≥ 8 |
| Write leftover electrons if electron < 8 |
| Shell M |
Write 18 if electron ≥ 18 |
| Write 8 if 8 ≥ electron < 18 |
| Write leftover electrons if electron < 8 |
| Shell N |
Write 32 if electron ≥ 32 |
| Write 18 if 18 ≥ electron < 32 |
| Write 8 if 8 ≥ electron < 18 |
| Write leftover electrons if electron < 8 |
How to Determine Electron Count
- Follow the rules
- If the electrons (aka atomic number) = 0, you're done.
Examples
 |
K
| L
| M
| N
|
| 2 |
4 |
|
|
|
K
| L
| M
| N
|
| 2 |
8 |
2 |
|
|
K
| L
| M
| N
|
| 2 |
8 |
18 |
5 |
