Helium (He)

Element 2 · noble gas · group 18, period 1

Electron shells, 2. The outer shell is highlighted - it is the only one that takes part in bonding.

Helium is element 2, a noble gas in group 18 and period 1. Its electron configuration is 1s2. That leaves 2 valence electrons in the outer shell, with the shells filling 2. Its outer shell is already full, so it does not normally form ions at all.

2 protons
2 valence e−
s-block

Properties

Atomic number	2
Symbol	He
Standard atomic weight	4.0026 u
Group	18
Period	1
Block	s-block
Category	noble gas
Electron configuration	1s²
Noble-gas notation	1s²
Electrons per shell	2
Valence electrons	2
Common ionic charge	none
Electronegativity (Pauling)	no accepted value
Protons / electrons	2 / 2

Electron configuration of helium

Orbitals fill from the lowest energy upward. Writing that out for helium gives 1s², which is 1s2 in plain text.

Subshell	Electrons	Capacity
1s	2	2

Helium ion charge

Helium does not normally form ions. Its outer shell is already full, so there is nothing to gain by losing or gaining an electron.

Common questions

How many valence electrons does helium have?

Helium has 2 valence electrons. For a main-group element the count is the group number minus 10, and helium is in group 18.

What is the electron configuration of helium?

1s2, or 1s2 written from the previous noble gas. Orbitals fill lowest energy first.

How many protons, electrons and neutrons does helium have?

A neutral helium atom has 2 protons and 2 electrons. Its standard atomic weight is 4.0026, so the most common isotope has about 2 neutrons.

See the ionic charge of every element →

How this page was produced. The configuration was built by filling orbitals in energy order from atomic number 2 alone, not looked up. The shell counts, the valence count and the charge all follow from it. Nothing on this page is written per element.