Electronic configuration of hydrogen

Electrons in each shell

Hydrogen has 1 electron arranged as 1 across 1 shell, which is why it sits in period 1.

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 Hydrogen's 1 electron in that order gives 1s¹.

Hydrogen at a glance

Atomic number	1
Symbol	H
Atomic mass	1.008 u
Group	1
Period	1
Block	s-block
Category	Non-metal
Valence electrons	1

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Other elements in group 1

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