Zinc - Zn

Zinc (Zn) is a bluish-white metal used to protect steel from corrosion and to manufacture alloys, batteries and industrial chemicals. It is also an essential nutrient, although excessive exposure can harm people and ecosystems. Its behaviour in water depends on its chemical form and the water chemistry.

Chemical properties · Uses and occurrence · Health effects · Environmental effects · Zinc in water and treatment

Chemical properties of zinc

Selected properties of zinc
Symbol / atomic number	Zn / 30
Group / period / block	12 / 4 / d
Standard atomic weight	65.38(2)
Electron configuration	[Ar] 3d¹⁰ 4s²
Common oxidation state	+2
Density (near room temperature)	7.134 g cm⁻³
Melting point	419.527 °C
Boiling point	907 °C
Electronegativity (Pauling)	1.65
Non-bonded atomic radius	0.201 nm
Covalent radius	0.120 nm
First ionisation energy	906.4 kJ mol⁻¹
Naturally occurring isotopes	⁶⁴Zn, ⁶⁶Zn, ⁶⁷Zn, ⁶⁸Zn, ⁷⁰Zn
CAS registry number	7440-66-6

Atomic weight follows CIAAW; the parentheses indicate uncertainty in the final digits. Physical properties follow the Royal Society of Chemistry. Atomic radii depend on their definition and should not be interchanged.

Banded mineral specimen illustrated on Lenntech's zinc page — Mineral illustration from Lenntech's zinc page; this is not a photograph of pure zinc metal.

Zinc belongs to group 12 of the periodic table. Its atoms and usual Zn²⁺ ions have filled d subshells. Zinc reacts with oxygen and dissolves in dilute non-oxidising acids with release of hydrogen. The metal and its compounds have different properties and hazards.

Uses, occurrence and history

A major use of zinc is galvanising: applying a protective coating to iron and steel. Other uses include die-cast components, roofing, batteries and alloys such as brass, which combines zinc with copper. Zinc oxide is used in rubber manufacture and in products including paints and cosmetics. Dietary supplements contain zinc compounds, rather than pieces of zinc metal.

The principal zinc ore is sphalerite, a zinc sulfide mineral. Zinc is obtained from mined ores and recovered from secondary materials. Production, reserves and recycling figures change over time; current statistics are available from the US Geological Survey.

Zinc compounds and brass were used long before modern chemistry. Metallic zinc was produced in India before it was isolated in Europe. Andreas Marggraf's work in 1746 is an important milestone in European zinc chemistry, rather than the first use of the metal worldwide.

Health effects of zinc

Zinc supports enzyme activity, immune function, DNA and protein synthesis, growth and wound healing. Deficiency can impair growth, appetite, taste and wound healing. Food sources include meat, shellfish, dairy products, legumes and whole grains; the amount absorbed varies with the diet.

Excessive intake can cause nausea, vomiting and abdominal discomfort. Prolonged high intake, particularly from supplements, can reduce copper absorption and lead to copper deficiency, including anaemia and neurological problems. Requirements depend on age, sex and life stage. See the dietary reference information and the NIH source below for context; supplementation should address individual needs. Zinc's essential role does not establish an anti-ageing benefit from taking extra zinc.

In the workplace, inhaling zinc oxide fumes, for example during welding of galvanised steel, can cause metal fume fever with fever, chills, muscle aches and cough. This is an inhalation-related illness, not an infection. Exposure prevention and appropriate occupational controls are important; symptoms after fume exposure warrant medical assessment.

Environmental effects of zinc

Zinc occurs naturally in rocks, soils, sediments and water. Mining, smelting, industrial discharges and runoff can increase local concentrations. It does not degrade into another element, but can change chemical form and move between dissolved material, particles, sediments and organisms.

Plants and animals need zinc, but excessive bioavailable concentrations can harm aquatic life, plant growth and soil organisms. Toxicity depends on exposure and local conditions, including pH, hardness and dissolved organic matter. Total zinc concentration alone does not fully describe ecological risk.

Aquatic organisms can accumulate zinc from water and food. This bioaccumulation should not be confused with biomagnification, an increase in concentration at successive food-chain levels. Evidence does not support a general claim that zinc consistently biomagnifies through aquatic food webs.

Zinc in water and water treatment

Zinc may enter water through mineral weathering, industrial sources or corrosion of galvanised pipes, fittings and storage tanks. WHO has not established a health-based drinking-water guideline for zinc at concentrations normally encountered. Its guidance notes that concentrations above approximately 3 mg/L may affect acceptability. This is an aesthetic consideration, not a universal safety threshold or a discharge limit. Applicable local requirements should guide assessment.

For drinking-water investigations, compare source-water and tap-water results to assess whether plumbing is contributing zinc. Corrosion control or replacement of affected materials may address the source. Analyse dissolved and total zinc as appropriate to distinguish dissolved contamination from zinc associated with particles.

Industrial wastewater treatment can use controlled chemical precipitation followed by clarification and filtration to separate the metal-bearing solids. Zinc hydroxide is amphoteric: it can dissolve at both low and sufficiently high pH, so simply adding more alkali can reduce removal. Complexing agents and other metals also affect treatment. Establish operating conditions through treatability tests and verify the final effluent; manage the resulting sludge appropriately.

Further guidance: Zinc in water (Zn + H₂O) and heavy-metal removal.

Zinc page last reviewed: 24 October 2026 by Lenntech.