Full configuration
1s²
There's no noble gas before it, so the short and full forms are the same.
Orbital diagram
1s↑↓
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
Helium's 1s is full with two electrons, so it's a noble gas even though it has only two valence electrons.
Nearby elements
Questions students ask
What is the electronic configuration of helium?
1s². Helium has atomic number 2.
How many electrons are in each shell of helium?
2 (K, L, M, N… shells in order).
How many unpaired electrons does helium have?
0 in the ground state, so helium atoms are diamagnetic.