Silicon (Si): Bohr Model, Protons, Neutrons & Electrons
Silicon is element number 14, a metalloid in group 14, period 3. Its atom has 14 protons, 14 neutrons and 14 electrons arranged in 3 shells: 2, 8, 4.
Protons, neutrons and electrons in silicon
The atomic number of silicon is 14, so every silicon atom has 14 protons. A neutral atom has the same number of electrons, 14. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For silicon-28, that is 28 − 14 = 14 neutrons. Silicon has 3 stable isotopes, with 14, 15, 16 neutrons.
How to draw the Bohr model of silicon
- Draw the nucleus and write 14 p⁺ and 14 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 4 electrons on it.
- Check: 2 + 8 + 4 = 14 electrons, the same as the number of protons.
Electron configuration
The electron configuration of silicon is [Ne] 3s² 3p². Its 4 outer electrons decide how it reacts: it usually shares electrons in covalent bonds.
Key facts about silicon
| Symbol | Si |
|---|---|
| Atomic number | 14 |
| Relative atomic mass | 28.085 |
| Group · period · block | group 14 · period 3 · p-block |
| Type | Metalloid |
| State at 25 °C | solid |
| Electron shells | 2, 8, 4 |
| Electron configuration | [Ne] 3s² 3p² |
| Valence electrons | 4 |
| Common ion | — |
| Electronegativity (Pauling) | 1.90 |
| First ionisation energy | 8.15 eV (786 kJ/mol) |
| Atomic radius (empirical) | 110 pm |
Where silicon sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does silicon have?
Silicon has 14 protons and 14 electrons (atomic number 14). Its most common isotope, silicon-28, has 28 − 14 = 14 neutrons.
What is the electron configuration of silicon?
[Ne] 3s² 3p². In shells that is 2, 8, 4.
How many valence electrons does silicon have?
4. Silicon is in group 14, and its outer shell holds 4 electrons.
Where is silicon on the periodic table?
In group 14, period 3, in the p-block. It is a metalloid.
