Electronic configuration of oxygen

Electrons in each shell

Oxygen has 8 electrons arranged as 2, 6 across 2 shells, which is why it sits in period 2.

How to write it

Electrons fill orbitals in order of increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p… Each s orbital holds 2 electrons, p holds 6 and d holds 10. Placing Oxygen's 8 electrons in that order gives 1s² 2s² 2p⁴.

Oxygen at a glance

Atomic number	8
Symbol	O
Atomic mass	15.999 u
Group	16
Period	2
Block	p-block
Category	Non-metal
Valence electrons	6

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Other elements in group 16

Elements in the same group have the same number of outer electrons, which is why they behave alike.