Tin
post transition metalProperties
| Property | Value |
|---|---|
| Atomic Mass | 118.71 amu |
| Category | post transition metal |
| Group | 14 |
| Period | 5 |
| Electron Configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p2 |
| Electronegativity | 1.96 (Pauling) |
| Oxidation States | 4, 2, -4 |
| Melting Point | 505.08 K (231.9 °C) |
| Boiling Point | 2875 K (2601.8 °C) |
| Density | 7.265 g/cm³ |
About Tin
Tin has been alloyed deliberately for about 5,000 years — bronze (Sn in Cu) was the metal that ended the Stone Age — and it's still doing the same job in a lab today: lower the melting point, improve castability, resist corrosion. The two allotropes matter. White β-Sn is the metal you handle above 13.2 °C; below that it slowly converts to grey α-Sn, a brittle diamond-cubic semiconductor, and the molar volume jumps about 27%. That's tin pest, which hollowed out Napoleon's army's buttons and Scott's Antarctic kerosene cans. In modern life, the biggest single use is reflow solder — Sn-Ag-Cu (SAC305) at 217 °C wets pads on every printed circuit board after the EU's RoHS directive killed Sn-Pb in consumer electronics. Float glass is poured onto a molten tin bath, and SnO₂:F is the transparent conductor on every low-emissivity window pane. The ¹⁰ stable isotopes are a quirk of Z = 50 sitting on a nuclear magic number.
Fun Fact
Tin holds ten stable isotopes — more than any other element. The accident is that Z = 50 is a nuclear magic number, so the proton shell closes and a wide range of neutron numbers can hang on without falling off the valley of stability.
Common Uses
- Sn-3.0Ag-0.5Cu (SAC305) lead-free reflow solder on PCB assembly lines
- Float-glass tin bath that gives plate glass its optically flat surface
- Fluorine-doped tin oxide (FTO) coatings on low-E windows and solar cells
- Tin-plated steel cans (tinplate) for acidic foods like tomatoes and citrus
- Pewter and Britannia metal castings (Sn–Sb–Cu) for tableware and figures
- Organotin catalysts (DBTDL) for crosslinking silicones and polyurethanes