Tin (Sn)
“The Bronze Age’s secret partner of copper — five thousand years on, it still guards the milk can and joins the circuits of Bangladesh.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
The notes
Characteristics
- Configuration [Kr] 4d¹⁰ 5s² 5p²: a post-transition metal of Group 14, Period 5, p-block, with four valence electrons and both +2 and +4 oxidation states (SnO and SnO₂).
- Allotropy with drama: above 13.2 °C white β-tin is a normal lustrous metal, but under lasting cold it crumbles into powdery grey α-tin — the decay called “tin pest”.
- It shrugs off water and mild acids, so a whisper-thin coat of tin keeps steel food cans safe for years on the shelf.
- It melts at only 232 °C and bends with the crackling “tin cry” — safe and pleasant to handle, yet it never occurs free in nature.
A soft, silvery-white metal with a faint yellow sheen, easily bent by hand or rolled into foil. Bend a bar and it crackles — the famous “tin cry”, the sound of twinned crystals slipping inside the metal.
Where you meet it
✦ Uses
- Tin-plating of steel food cans — the familiar “tins” of condensed milk, fish and fruit on Bangladeshi shop shelves.
- Solders for electronics, from the classic tin-lead to modern lead-free tin-silver-copper alloys that join every phone’s circuit board.
- Bronze (copper-tin) for bells, statues and coins; pewter tableware; and molten-tin baths on which window glass is floated perfectly flat.
- Stannous fluoride (SnF₂) in toothpaste against cavities, and organotin stabilisers that keep PVC pipes and plastics from crumbling in sunlight.
◍ Everyday examples
- A condensed-milk or canned-fish “tin” in a Bangladeshi kitchen is simply steel wearing a whisper-thin coat of tin.
- Inside TVs, phones and radios, components are joined by seams of tin-based solder.
- A bronze bell at a school or temple — and the classroom trick of bending a tin strip until it “cries”.
History & name
Tin has no lone discoverer: alloyed with copper it created bronze around 3000 BCE and gave a whole age of history its name. Ancient traders risked long sea voyages for the tin streams of Cornwall and the mines of the East, dealing in cassiterite (SnO₂) — the dense, black “tinstone” that is still tin’s only important ore. The symbol Sn descends from stannum, the Romans’ name for the metal.