Zinc (Zn)

Galvanising works because zinc is more reactive than steel, not less: the coating corrodes preferentially and protects the steel even where the surface is scratched through. Zinc is essential to human life in a way that shows up fast — it sits in the active site of hundreds of enzymes, and deficiency is a major cause of childhood stunting and diarrhoeal deaths worldwide. A US cent minted since 1982 is 97.5% zinc, about 2.4 grams of it, under a copper plating that makes up the other 2.5%.

Properties

Atomic number

30

Symbol

Zn

Standard atomic weight

65.38 u

Category

Transition metal

Group

12

Period

4

Block

d-block

Electron configuration

[Ar] 4s² 3d¹⁰

Electrons per shell

2, 8, 18, 2

Melting point

692.68 K — 419.5 °C — 787.2 °F

Boiling point

1,180 K — 906.9 °C — 1664.3 °F

Density

7.134 g/cm³

Electronegativity

1.65 (Pauling)

Oxidation states

+2

Discovered

1746 by Andreas Sigismund Marggraf

Electron configuration

Full

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰

Noble gas shorthand

[Ar] 4s² 3d¹⁰

Shells

K: 2 · L: 8 · M: 18 · N: 2

What it is used for

• Galvanising steel against rust — about half of all zinc used
• Brass, which is copper and zinc
• Die castings for door furniture, carburettors and toy cars
• Zinc oxide in sunscreen, nappy cream and rubber manufacture
• The anode in alkaline and zinc-air batteries

Filed as a transition metal because it is in the d-block and every school table colours it that way. Under IUPAC's strict definition it is not one: zinc's d subshell is full in the metal and in every zinc compound, and the same argument applies to cadmium and mercury.

Neighbours in the table

Group 12

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Zinc sits in group 12 with cadmium, mercury, copernicium.