Silicon (Si)
Metalloid
Silicon is the metalloid the digital world is built on. It is the second most abundant element in the crust — most sand is silicon dioxide — and ultra-pure silicon crystals form the chips inside every computer and phone.
Position on the periodic table
Atomic properties
| Atomic number | 14 |
|---|---|
| Atomic mass | 28.085 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p2 |
| Noble gas shorthand | [Ne] 3s2 3p2 |
| Electrons per shell | 2, 8, 4 |
| Valence electrons (outer shell) | 4 |
| Common oxidation states | +4, -4 |
| Electronegativity (Pauling) | 1.9 |
| Covalent radius (approx.) | 111 pm |
| First ionization energy | 786.5 kJ/mol |
| Electron affinity | 134.1 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 2.329 g/cm³ |
| Melting point | 1413.8 °C (1687 K) |
| Boiling point | 3264.8 °C (3538 K) |
| Appearance | crystalline, reflective with bluish-tinged faces |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of silicon
Silicon's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p2, usually shortened to [Ne] 3s2 3p2. Its electrons occupy 3 shells (2, 8, 4), placing it in period 3 of the p-block. The 4 outer-shell electrons drive its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of silicon
- Semiconductor chips and solar cells
- Glass, ceramics and cement
- Silicones for sealants, cookware and medical implants
- Alloying element that strengthens aluminium
Biological role: Important for some organisms (diatoms build glassy silica shells); trace role in humans under study.
Occurrence: About 28% of the Earth's crust, always combined — mainly as silica and silicate minerals.
Common compounds of silicon
SiO2
Silicon dioxide (quartz, sand)
SiC
Silicon carbide
Na2SiO3
Sodium silicate (water glass)
History and discovery
Discovered: 1824 — Jöns Jacob Berzelius. Name origin: From Latin silex, meaning flint (a hard silica rock).
Jöns Jacob Berzelius isolated pure silicon in 1824, though its oxide had been studied for decades before.
Safety notes
Solid silicon is harmless, but breathing fine silica dust over long periods causes lung disease (silicosis).
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Silicon
1. What is the chemical symbol of Silicon?
2. What is the atomic number of Silicon?
3. Which category does Silicon belong to?
4. What is the state of Silicon at room temperature?
5. Which period of the periodic table is Silicon in?
Silicon FAQs
What is the atomic number of silicon?
Silicon's atomic number is 14 — every silicon atom has 14 protons in its nucleus.
What is the symbol for silicon?
Si. From Latin silex, meaning flint (a hard silica rock).
Is silicon a metal, nonmetal, or metalloid?
Silicon is classified as a metalloid — an element with properties between metals and nonmetals.
What state is silicon at room temperature?
At about 25 °C, silicon is a solid. It melts at 1413.8 °C.
How many valence electrons does silicon have?
Silicon has 4 electrons in its outer shell (shell pattern: 2, 8, 4).
What is silicon used for?
Key uses include: semiconductor chips and solar cells; glass, ceramics and cement; silicones for sealants, cookware and medical implants.
Related elements
Keep working with this element
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