Element 14 · Silicon (Si)

Silicon Bohr model: diagram and electrons per shell

The silicon Bohr model shows a silicon atom (Si) as a small nucleus with its electrons circling it in 3 shells: 2 in shell K, 8 in shell L and 4 in shell M. This page has a rotating 3D silicon Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the silicon Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of silicon (Si), a simplified picture of a single silicon atom. Its nucleus holds 14 protons, and a neutral silicon atom has 14 electrons, arranged around it in 3 shells (2 in shell K, 8 in shell L and 4 in shell M).

Si K · 21s² L · 82s² 2p⁶ M · 43s² 3p²

Silicon Bohr model diagram

Bohr model diagram of silicon: a nucleus of 14 protons with 14 electrons on 3 shells, 2 in shell K, 8 in shell L and 4 in shell M, each ring labelled with its shell letter. — The silicon Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L and 4 in shell M).

Silicon electrons per shell

A neutral silicon atom has 14 electrons, one for each of its 14 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L and 4 in shell M.

Electrons in each shell of the silicon Bohr model
Shell	Shell number (n)	Electrons	Most it can hold (2n²)	Subshells
K	1	2	2	1s²
L	2	8	8	2s² 2p⁶
M	3	4	18	3s² 3p²

How the silicon Bohr model builds up, shell by shell

Watch the silicon Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L and 4 in shell M) as it forms.

Animation of the silicon Bohr model being built: a nucleus of 14 protons appears first, then each shell grows in around it and takes its electrons, giving 14 electrons on 3 shells (2 in shell K, 8 in shell L and 4 in shell M). — The silicon Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L and 4 in shell M. Protons are red, neutrons yellow and electrons blue.

How to draw the silicon Bohr model

Find the atomic number. Silicon has atomic number 14, so a neutral atom has 14 protons and 14 electrons.
Draw the nucleus. Put a circle in the centre and write Si in it. The 14 protons sit there with the neutrons.
Draw the shells. Sketch 3 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L and 4 in shell M.
Check the total. 2 + 8 + 4 = 14, the atomic number, so every electron is accounted for.

Atomic data for the silicon Bohr model

The numbers behind the silicon Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol: Si
Atomic number: 14
Atomic mass: 28.085 u
Family: Metalloids
Position: group 14, period 3
Block: p-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p²
Shorthand: [Ne] 3s² 3p²
Electrons per shell: 2, 8, 4
Outer-shell electrons: 4 in shell M

Ionisation energies

I₁: 786.5
I₂: 1577.1
I₃: 3231.6
I₄: 4355.5
I₅: 16091
I₆: 19805
I₇: 23780
I₈: 29287

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Calculated (pm): 111
Empirical (pm): 110
Covalent (pm): 116
Van der Waals (pm): 210

Electronegativity and electron affinity

Electronegativity (Pauling): 1.9
Electron affinity (kJ/mol): 134.068

Oxidation states

−4 +4

Charges the element commonly takes in compounds.

Physical properties, abundance and history of silicon

Bulk properties of silicon, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions: Solid
Appearance: Crystalline, reflective with bluish-tinged faces
Melting point: 1413.85°C (1687 K)
Boiling point: 3264.85°C (3538 K)
Density: 2.329 g/cm³
Thermal conductivity (W/m·K): 149
Specific heat (J/g·K): 0.712
Molar heat capacity (J/mol·K): 19.789
Heat of fusion (kJ/mol): 50.6
Heat of vaporisation (kJ/mol): 383

Abundance

Earth's crust (mg/kg): 282000
Oceans (mg/L): 2.2

Discovery

Discovered by: Jöns Jacob Berzelius
Year: 1824
Named by: Thomas Thomson (chemist)

Common compounds

Silica O2Si
Silicon Si
3-(Trimethoxysilyl)propyl methacrylate C10H20O5Si
Flusilazole C16H15F2N3Si
Sodium Silicate Na2O3Si
Silicon carbide CSi
Tetraethoxysilane C8H20O4Si
Chlorotrimethylsilane C3H9ClSi

Compounds listed in the PubChem database.

Main isotopes of silicon

Isotopes of silicon share the same 14 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of silicon: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
28	92.254 %	stable	–
29	4.672 %	stable	–
30	3.074 %	stable	–
31	–	157.16 min	β⁻
32	–	157 y	β⁻
33	–	6.18 s	β⁻

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about silicon

Silicon on the periodic table – properties, isotopes, uses and the full silicon page.
Metalloids – all metalloid elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.