Beryllium (Be)
Element 4 · alkaline earth metal · group 2, period 2
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
Beryllium Lewis dot structure
Beryllium has 2 valence electrons, so its Lewis symbol carries 2 dots: two single dots. The dots go one to a side before any of them pair up, so the unpaired ones show exactly how many bonds the atom tends to form. The ion has given those electrons away, which is why it is drawn in brackets with none.
Draw it in the Lewis structure generator →
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
What is the Lewis dot structure of beryllium?
The symbol Be with 2 dots, one for each valence electron: two single dots. Dots go one to a side before any pair up, the same way electrons fill separate orbitals before sharing one. The Be2+ ion is drawn in brackets with no dots, because it has lost them.
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.
Beryllium in Lewis structures
What the configuration above means in practice. Beryllium brings 2 valence electrons to it, and the working there starts by counting exactly that.
Nearby elements
See the ionic charge of every element →