Quick Facts
| Property | Value |
|---|---|
| Symbol | Zn |
| Atomic Number | 30 |
| Atomic Mass | 65.38 u |
| Category | Transition Metal |
| Period | 4 |
| Group | 12 |
| Block | d |
| Electron Configuration | [Ar] 3d¹⁰ 4s² |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Solid |
| Density | 7.14 g/cm³ |
| Melting Point | 419.53°C (692.68 K) |
| Boiling Point | 907°C (1180 K) |
| Appearance | Bluish-white, lustrous metal |
Atomic Properties
| Property | Value |
|---|---|
| Electron Configuration | [Ar] 3d¹⁰ 4s² |
| Electronegativity | 1.65 (Pauling scale) |
| First Ionization Energy | 906.4 kJ/mol |
| Atomic Radius | 134 pm |
| Covalent Radius | 122 pm |
| Van der Waals Radius | 139 pm |
History and Discovery
Discovered by: Andreas Sigismund Marggraf (isolated) Year of Discovery: 1746 Location: Berlin, Germany
Etymology
The name "zinc" probably comes from German "Zinke" meaning "pointed" or "tooth-like," referring to the pointed crystals in furnace residues.
Discovery Story
Zinc was used in brass alloys since ancient times. Indian metallurgists produced zinc around 1200 CE. Andreas Marggraf isolated pure zinc in 1746 by heating calamine ore with charcoal in a closed vessel. William Champion had established zinc production in England in 1743.
Isotopes
| Isotope | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|
| ⁶⁴Zn | 49.17% | Stable | - |
| ⁶⁶Zn | 27.73% | Stable | - |
| ⁶⁷Zn | 4.04% | Stable | - |
| ⁶⁸Zn | 18.45% | Stable | - |
| ⁷⁰Zn | 0.61% | Stable | - |
Occurrence
Natural Abundance
Zinc is the 24th most abundant element in Earth's crust (75 ppm). The main ore is sphalerite (ZnS). Major producers are China, Peru, Australia, and the United States. Zinc often occurs with lead and copper ores.
Extraction and Production
- Roast-Leach-Electrowin: Primary process for sphalerite
- Imperial Smelting Process: For mixed lead-zinc ores
- Sources: Zinc mining worldwide
- Global production: about 13 million tons annually
Applications and Uses
Galvanizing
- Corrosion protection for steel (50% of use)
- Hot-dip galvanizing
- Electrogalvanizing
- Construction and infrastructure
Alloys
- Brass (copper-zinc)
- Die-casting alloys
- Zamak alloys
- Coinage alloys
Chemicals
- Zinc oxide (rubber, cosmetics, sunscreen)
- Zinc chloride (flux, batteries)
- Zinc sulfate (agriculture)
Other Uses
- Batteries (zinc-carbon, alkaline)
- Dietary supplements
- Roofing materials
Biological Role
Zinc is essential for all living organisms. It is a component of hundreds of enzymes and transcription factors.
In the Human Body
- About 2-3 g in adult body
- Essential for over 300 enzymes
- Important for immune function
- Required for DNA synthesis
- Crucial for wound healing
- Daily requirement: 8-11 mg
Dietary Sources
Oysters, beef, crab, pork, beans, and fortified cereals are good zinc sources.
Safety and Hazards
Toxicity
Zinc is essential but toxic in excess. Zinc fumes cause "metal fume fever" (zinc shakes). Excessive supplementation can cause copper deficiency.
Handling Precautions
- Zinc fumes from welding/melting are hazardous
- Fine zinc powder is flammable
- Zinc chloride is corrosive
- Follow occupational exposure limits
Environmental Impact
Zinc mining can contaminate soil and water. Galvanized materials can leach zinc. Excess zinc is toxic to aquatic life.
Interesting Facts
- Zinc is the 24th most abundant element but the 4th most used metal (after iron, aluminum, copper)
- A US penny minted after 1982 is 97.5% zinc with copper plating
- Zinc deficiency affects about 2 billion people worldwide
- Galvanizing was first patented in 1837
- The human body contains about 2-3 grams of zinc