Sodium (Na): Bohr Model, Protons, Neutrons & Electrons
Sodium is element number 11, an alkali metal in group 1, period 3. Its atom has 11 protons, 12 neutrons and 11 electrons arranged in 3 shells: 2, 8, 1.
Protons, neutrons and electrons in sodium
The atomic number of sodium is 11, so every sodium atom has 11 protons. A neutral atom has the same number of electrons, 11. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For sodium-23, that is 23 − 11 = 12 neutrons.
How to draw the Bohr model of sodium
- Draw the nucleus and write 11 p⁺ and 12 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 1 electron on it.
- Check: 2 + 8 + 1 = 11 electrons, the same as the number of protons.
Electron configuration
The electron configuration of sodium is [Ne] 3s¹. Its 1 outer electron decides how it reacts: it tends to lose it, forming Na⁺ ions.
Key facts about sodium
| Symbol | Na |
|---|---|
| Atomic number | 11 |
| Relative atomic mass | 22.99 |
| Group · period · block | group 1 · period 3 · s-block |
| Type | Alkali Metal |
| State at 25 °C | solid |
| Electron shells | 2, 8, 1 |
| Electron configuration | [Ne] 3s¹ |
| Valence electrons | 1 |
| Common ion | Na⁺ |
| Electronegativity (Pauling) | 0.93 |
| First ionisation energy | 5.14 eV (496 kJ/mol) |
| Atomic radius (empirical) | 180 pm |
Where sodium sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does sodium have?
Sodium has 11 protons and 11 electrons (atomic number 11). Its most common isotope, sodium-23, has 23 − 11 = 12 neutrons.
What is the electron configuration of sodium?
[Ne] 3s¹. In shells that is 2, 8, 1.
How many valence electrons does sodium have?
1. Sodium is in group 1, and its outer shell holds 1 electron.
Where is sodium on the periodic table?
In group 1, period 3, in the s-block. It is an alkali metal.
