Sodium (Na)
Element 11 · alkali metal · group 1, period 3
Sodium is element 11, a alkali metal in group 1 and period 3. Its electron configuration is [Ne] 3s1. That leaves 1 valence electron in the outer shell, with the shells filling 2, 8, 1. Losing its 1 valence electron is the shorter route to a full shell, so it carries a charge of +1.
- 11 protons
- 1 valence e−
- +1
- s-block
Properties
| Atomic number | 11 |
|---|---|
| Symbol | Na |
| Standard atomic weight | 22.99 u |
| Group | 1 |
| Period | 3 |
| Block | s-block |
| Category | alkali metal |
| Electron configuration | 1s2 2s2 2p6 3s1 |
| Noble-gas notation | [Ne] 3s1 |
| Electrons per shell | 2, 8, 1 |
| Valence electrons | 1 |
| Common ionic charge | +1 |
| Electronegativity (Pauling) | 0.93 |
| Protons / electrons | 11 / 11 |
Electron configuration of sodium
Orbitals fill from the lowest energy upward. Writing that out for sodium gives 1s2 2s2 2p6 3s1, which is 1s2 2s2 2p6 3s1 in plain text.
Everything up to Ne is the same as in that noble gas, so it is usually abbreviated to [Ne] 3s1. The part outside the bracket is what does the chemistry.
| Subshell | Electrons | Capacity |
|---|---|---|
| 1s | 2 | 2 |
| 2s | 2 | 2 |
| 2p | 6 | 6 |
| 3s | 1 | 2 |
Sodium ion charge
Sodium commonly forms ions with a charge of +1.
It has 1 valence electron, so it is 7 short of a full octet and 1 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 sodium have?
Sodium has 1 valence electron. For groups 1 and 2 the count is the group number, and sodium is in group 1.
What is the electron configuration of sodium?
1s2 2s2 2p6 3s1, or [Ne] 3s1 written from the previous noble gas. Orbitals fill lowest energy first.
What is the charge of sodium?
Sodium commonly forms ions with a charge of +1. With 1 valence electron it is 7 short of an octet and 1 above an empty shell, so it takes whichever route is shorter.
How many protons, electrons and neutrons does sodium have?
A neutral sodium atom has 11 protons and 11 electrons. Its standard atomic weight is 22.99, so the most common isotope has about 12 neutrons.
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