Tin ($\mathrm{Sn}$)

Tin is the chemical element with atomic number 50 and symbol $\mathrm{Sn}$. It is a metal. Both $+2$ and $+4$ oxidation states are common. Its different solid allotropes have different structures, and tin-containing solders illustrate how alloy composition can change melting and mechanical properties.^[ref]

The brown or brown-black sulfide formed from suitable tin(II) solutions.

The yellow sulfide used in qualitative recognition of suitable tin(IV) solutions.

A tin oxide whose hydrated forms may precipitate through hydrolysis of suitable tin(IV) solutions.

The +4 oxidation state of tin. The actual aqueous species can depend on pH, hydrolysis and ligands; a bare ionic formula is an analytical shorthand.

The +2 oxidation state of tin. The actual aqueous species can depend on pH, hydrolysis and ligands; a bare ionic formula is an analytical shorthand.

Degradation associated with the slow transformation of white tin to lower-density grey tin. Nucleation, impurities and thermal history strongly affect its kinetics.

The diamond-cubic form of tin favoured below about $13{}^{\circ }\mathrm{C}$ at ambient pressure. Its lower density than white tin contributes to the damage associated with tin pest.

The metallic tetragonal form of tin stable near ordinary room temperature at ambient pressure.

$\mathrm{S}{\mathrm{n}}_5^{2-}$, a five-vertex trigonal-bipyramidal Zintl cluster. Removing five mainly s-rich lone pairs from its 22 valence electrons leaves 12 skeletal electrons.