Silicon (Si)
“From ordinary beach sand to the thinking brain of every computer and phone — silicon is the metalloid that runs the modern world.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
The notes
Characteristics
- Configuration [Ne] 3s² 3p² — Period 3, Group 14, p-block, with four valence electrons, so like carbon it builds four covalent bonds in its crystals and compounds.
- Second most abundant element in the Earth’s crust after oxygen (about 28% by mass), yet never found uncombined: every grain of sand and most rocks are its oxides and silicates.
- A true semiconductor — far less conductive than a metal, but warming it, or sprinkling in traces of boron or phosphorus, raises its conductivity, exactly the opposite of a metal’s behaviour.
- Chemically guarded like aluminium: any fresh surface instantly grows a thin SiO₂ film, which is why silicon shrugs off acids (except HF) and weathers so slowly.
A hard, brittle, blue-grey solid with a shiny, metal-like lustre — yet not a metal at all but a metalloid, halfway in character between the metals on its left and the nonmetals on its right. Grown for industry as long, dark, mirror-smooth single-crystal cylinders, it is sliced by the thousand into paper-thin wafers; in its amorphous form it is merely a brown powder.
Where you meet it
✦ Uses
- Computer and smartphone chips — every processor and memory chip is carved from a paper-thin wafer of single-crystal silicon, its conductivity fine-tuned by doping with boron and phosphorus.
- Solar (photovoltaic) panels — the solar home systems that light the off-grid chars, haors and hill tracts of Bangladesh all lean on silicon wafers that turn sunlight straight into electricity.
- Glass — melting quartz sand (SiO₂) with soda ash and limestone makes the soda-lime glass of windows, bottles and every flask in a school laboratory.
- Silicone sealants and greases — the rubbery sealing bead around bathroom tiles, the grease inside phone cases and baking moulds all come from silicon-based silicone polymers.
◍ Everyday examples
- A handful of sand from Cox’s Bazar beach is mostly grains of quartz — crystalline silicon dioxide — polished smooth by the waves of the Bay of Bengal.
- Every concrete wall, clay brick and granite doorstep of a Bangladeshi town is packed with silicate minerals built around silicon atoms.
- The dark chip beneath a phone’s back cover and the blue-black panel on a village roof are both silicon doing its two most famous jobs.
History & name
In 1811 the French chemists Joseph Gay-Lussac and Louis Thénard heated silicon tetrafluoride with potassium and caught an impure brownish solid — humanity’s first glimpse of silicon. It was Sweden’s Jöns Jacob Berzelius who, in 1824, repeated the attack with potassium fluorosilicate and molten potassium, washing away the by-products to isolate the element in recognisable form. Humphry Davy, believing the newcomer a metal, had proposed calling it silicium; in 1817 the Scottish chemist Thomas Thomson countered that it behaved more like carbon and boron, and his ending -on is the one that survived.