Tin (Sn)
Tin (Sn) is a post-transition metal with atomic number 50 and a standard atomic weight of 118.71. At room temperature it is a solid that melts at 232 °C and boils at 2,586 °C.
Tin key facts
Tin at a glance
Identity
| Symbol | Sn |
|---|---|
| Atomic number (Z) | 50 |
| Atomic weight | 118.71 ± 0.01 (CIAAW 2024) |
| Category | Post-transition metal |
| Group | 14 — carbon group |
| Period | 5 |
| Block | p-block |
| CAS number | 7440-31-5 |
Atomic properties
| Electron configuration | [Kr] 4d10 5s2 5p2 Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p2 |
|---|---|
| Electrons per shell | 2, 8, 18, 18, 4 |
| Oxidation states | -4, +2, +4 Less common: -3, -2, -1, 0, +1, +3 |
| Electronegativity (Pauling) | 1.96 |
| First ionisation energy | 7.344 eV (708.6 kJ/mol) 2nd: 14.633 eV · 3rd: 30.506 eV |
| Electron affinity | 1.112 eV |
| Atomic radius (empirical) | 145 pm |
| Covalent radius | 140 pm |
| Van der Waals radius | 217 pm |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Melting point | 231.9 °C · 449.5 °F · 505.08 K |
| Boiling point | 2,586 °C · 4,686.8 °F · 2,859.15 K |
| Density | 7.287 g/cm³ |
| Specific heat capacity | 0.227 J/(g·K) |
| Thermal conductivity | 66.8 W/(m·K) |
| Crystal structure | Tetragonal |
Isotopes & abundance
| Natural occurrence | Primordial |
|---|---|
| Radioactive | No |
| Natural isotopes (abundance) | 120Sn 32.58%, 118Sn 24.22%, 116Sn 14.54%, 119Sn 8.59%, 117Sn 7.68%, 124Sn 5.79% |
| Stable isotopes | 10 |
| Known isotopes | 42 |
| Abundance in Earth's crust | 2.3 mg/kg |
| Abundance in seawater | 0.000004 mg/L |
Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.
Tin electron configuration
Tin has 50 electrons. Written in short form, its ground-state configuration is [Kr] 4d10 5s2 5p2 — the electrons of the noble gas krypton, plus 4d10 5s2 5p2.Written out in full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p2.
As a member of group 14 it has 4 valence electrons in its outer shell (shell 5), which largely decide its chemistry.
Discovery and name
Prehistoric — Known since antiquity (in bronze from c. 3000 BC).
Anglo-Saxon tin; the symbol Sn is from Latin stannum.
Known for
Used in solder, tinplate (steel cans coated with tin) and bronze. Below 13.2 °C white tin slowly turns into brittle grey tin ('tin pest').
Isotopes of tin
Naturally occurring tin is a mix of 10 isotopes. Each has 50 protons; they differ in the number of neutrons:
| Isotope | Protons | Neutrons | Natural abundance | Stability |
|---|---|---|---|---|
| 120Sn | 50 | 70 | 32.58% | stable |
| 118Sn | 50 | 68 | 24.22% | stable |
| 116Sn | 50 | 66 | 14.54% | stable |
| 119Sn | 50 | 69 | 8.59% | stable |
| 117Sn | 50 | 67 | 7.68% | stable |
| 124Sn | 50 | 74 | 5.79% | stable |
| 122Sn | 50 | 72 | 4.63% | stable |
| 112Sn | 50 | 62 | 0.97% | stable |
| 114Sn | 50 | 64 | 0.66% | stable |
| 115Sn | 50 | 65 | 0.34% | stable |
42 isotopes of tin are known in our data set (half-lives as published in nuclear data tables).
Tin compared with group 14
The other elements in group 14 (carbon group), from top to bottom of the table:
| Element | Z | Atomic weight | Melting point | Boiling point | Density | Electronegativity |
|---|---|---|---|---|---|---|
| Carbon | 6 | 12.011 | — | 3,642 °C | 2.2 g/cm³ | 2.55 |
| Silicon | 14 | 28.085 | 1,414 °C | 3,265 °C | 2.33 g/cm³ | 1.9 |
| Germanium | 32 | 72.630 | 938 °C | 2,833 °C | 5.323 g/cm³ | 2.01 |
| Tin | 50 | 118.71 | 232 °C | 2,586 °C | 7.287 g/cm³ | 1.96 |
| Lead | 82 | 207.2 | 327 °C | 1,749 °C | 11.3 g/cm³ | 2.33 |
| Flerovium | 114 | [290] | — | — | 9.928 g/cm³ (pred.) | — |