ChemSphere
30Zn65.382

Zinc

Transition metal · Period 4 · Group 12 · d-block

The sacrificial metal that keeps steel from rusting

Atomic mass
65.382 u
State at 25 °C
Solid
Electronegativity
1.65
Melting point
419.5 °C
Boiling point
906.9 °C
Configuration
[Ar] 3d10 4s2
Building atom…
30 protons 35 neutrons 30 electrons

Zinc, explained

Video lesson in production

Bhavya’s explainer for this element will play here.

Overview

Zinc ([Ar]3d10 4s2) loses only its two 4s electrons, so all its compounds contain Zn2+. Because that ion keeps a completely filled d subshell, zinc compounds are colorless, and zinc is often left out of the true transition metals; its chemistry resembles magnesium's. Zinc hydroxide is amphoteric, dissolving in both acids and strong bases. Zinc is more reactive than iron, which is the key to its biggest use: a zinc coating on steel corrodes first, sacrificing itself and protecting the iron even where the coating is scratched.

Zinc is a bluish-white metal that melts at 419.5 °C and boils at 907 °C, low enough that it can be distilled. About half of the zinc produced is used to galvanize steel. The rest goes into brass, precision die-cast parts, batteries, and zinc oxide, which is used in rubber tires, sunscreens and ointments. Zinc is also essential to life: about one in ten human proteins binds zinc.

Discovery

Brass was made in antiquity by heating copper with zinc ores, long before metallic zinc was identified. Indian metallurgists at Zawar in Rajasthan were distilling zinc metal on a large scale by medieval times, and China produced it later. In Europe, William Champion patented a zinc smelting process in 1738, and Andreas Marggraf described the isolation of pure zinc in 1746. The name comes from the German Zink, possibly from Zinke, a prong, describing the jagged crystals of the metal.

Where it’s found
Zinc makes up about 70 ppm of the crust and is mined mainly as sphalerite (ZnS), often alongside lead, with China, Peru and Australia the largest producers.
What it’s used for
  • Galvanizing steel
  • Brass
  • Die-cast parts
  • Batteries
  • Zinc oxide in rubber and sunscreen
  • Dietary supplements
In living things
Zinc is essential: it is needed by more than 300 enzymes, including carbonic anhydrase, and by zinc-finger proteins that regulate genes. Deficiency impairs growth, immunity and wound healing.
Safety
Zinc has low toxicity, but breathing zinc oxide fumes, for example when welding galvanized steel, causes metal fume fever. Long-term excess zinc intake can cause copper deficiency.

How it compares

Where Zinc sits among all 118 elements on the trends that shape the table.

  • Electronegativity1.65Pauling

    #47 of 100 elements with data

  • Ionization energy906kJ/mol

    #20 of 104 elements with data

  • Atomic radius135pm

    #59 of 95 elements with data

  • Electron affinity-58kJ/mol

    #100 of 109 elements with data

  • Density7.14g/cm³

    #64 of 114 elements with data

  • Melting point693K

    #75 of 110 elements with data

Density
7.14 g/cm³
Atomic radius
135 pm
Covalent radius
118 pm
Molar heat
25.47 J/(mol·K)
Appearance
silver-gray
Discovered by
India

Inside the atom

30 electrons arranged in 4 shells: 2 · 8 · 18 · 2.

Orbital diagram

1s2 2s2 2p6 3s2 3p6 4s2 3d10 · shorthand [Ar] 3d10 4s2

  1. 1s2
  2. 2s2
  3. 2p6
  4. 3s2
  5. 3p6
  6. 4s2
  7. 3d10

Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Zinc bonds.

Ionization energies

Energy to remove each electron in turn, on a log scale. The biggest leap, from electron 20 to 21 (×2.5), is where the next electron has to come from a filled shell much closer to the nucleus.

Signature reactions

The chemistry Zinc is known for.

  1. Redox · Metal extraction

    Roasting zinc blende

    Zinc sulfide ore is roasted to zinc oxide before the metal is recovered, usually by dissolving it in sulfuric acid and electrolysing. The sulfur dioxide by-product is captured to make sulfuric acid.

    2ZnS(s)+3O2(g)2ZnO(s)+2SO2(g)

    Conditions: about 900 °C in air

  2. Redox · Electrochemistry

    Daniell cell

    Zinc gives electrons to copper ions, producing about 1.10 volts. Placed directly in copper sulfate solution, zinc becomes coated with copper as the blue color fades. John Frederic Daniell's 1836 cell was an early practical battery for telegraphs.

    Zn(s)+Cu2+(aq)Zn2+(aq)+Cu(s)

    Conditions: separate half-cells joined by a salt bridge

  3. Acid–base · Complex formation

    Amphoteric zinc hydroxide

    White zinc hydroxide precipitate redissolves in excess alkali to form the colorless tetrahydroxozincate ion. It also dissolves in acid, so zinc hydroxide behaves as both a base and an acid.

    Zn(OH)2(s)+2OH−(aq)[Zn(OH)4]2−(aq)

    Conditions: excess sodium hydroxide solution

Where you’ll meet it

Research

No research on Zinc yet

When Bhavya publishes a project that studies Zinc, it will be linked here.

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