Beryllium (Be)

Element 4 · alkaline earth metal · group 2, period 2

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

Beryllium is element 4, a alkaline earth metal in group 2 and period 2. Its electron configuration is [He] 2s2. That leaves 2 valence electrons in the outer shell, with the shells filling 2, 2. Losing its 2 valence electrons is the shorter route to a full shell, so it carries a charge of +2.

4 protons
2 valence e−
+2
s-block

Properties

Atomic number	4
Symbol	Be
Standard atomic weight	9.0122 u
Group	2
Period	2
Block	s-block
Category	alkaline earth metal
Electron configuration	1s² 2s²
Noble-gas notation	[He] 2s²
Electrons per shell	2, 2
Valence electrons	2
Common ionic charge	+2
Electronegativity (Pauling)	1.57
Protons / electrons	4 / 4

Electron configuration of beryllium

Orbitals fill from the lowest energy upward. Writing that out for beryllium gives 1s² 2s², which is 1s2 2s2 in plain text.

Everything up to He is the same as in that noble gas, so it is usually abbreviated to [He] 2s². The part outside the bracket is what does the chemistry.

Subshell	Electrons	Capacity
1s	2	2
2s	2	2

Beryllium ion charge

Beryllium commonly forms ions with a charge of +2.

It has 2 valence electrons, so it is 6 short of a full octet and 2 above an empty outer shell. An atom takes whichever route is shorter, which is why the charge comes out as it does.

Common questions

How many valence electrons does beryllium have?

Beryllium has 2 valence electrons. For groups 1 and 2 the count is the group number, and beryllium is in group 2.

What is the electron configuration of beryllium?

1s2 2s2, or [He] 2s2 written from the previous noble gas. Orbitals fill lowest energy first.

What is the charge of beryllium?

Beryllium commonly forms ions with a charge of +2. With 2 valence electrons it is 6 short of an octet and 2 above an empty shell, so it takes whichever route is shorter.

How many protons, electrons and neutrons does beryllium have?

A neutral beryllium atom has 4 protons and 4 electrons. Its standard atomic weight is 9.0122, so the most common isotope has about 5 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 4 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.