Full configuration
1s² 2s² 2p²
In the short form, [He] stands for the 2 electrons of helium, the noble gas before carbon. Only the electrons after it are written out.
Orbital diagram
1s↑↓
2s↑↓
2p↑↑
Outer subshells only. Each box is an orbital; electrons fill singly first (Hund's rule), then pair up with opposite spins.
What the configuration tells you
Carbon has two unpaired 2p electrons in its ground state, but in compounds it promotes a 2s electron to get four, which is why it forms four bonds.
Nearby elements
| Z | Element | Configuration |
|---|---|---|
| 3 | Lithium | [He] 2s¹ |
| 4 | Beryllium | [He] 2s² |
| 5 | Boron | [He] 2s² 2p¹ |
| 7 | Nitrogen | [He] 2s² 2p³ |
| 8 | Oxygen | [He] 2s² 2p⁴ |
| 9 | Fluorine | [He] 2s² 2p⁵ |
Questions students ask
What is the electronic configuration of carbon?
[He] 2s² 2p², or in full, 1s² 2s² 2p². Carbon has atomic number 6.
How many electrons are in each shell of carbon?
2, 4 (K, L, M, N… shells in order).
How many unpaired electrons does carbon have?
2 in the ground state, so carbon atoms are paramagnetic.