Zinc (Zn)

Zinc (Zn) is a metal with atomic number 30 located in group 12 of the periodic table. This bluish-white, brittle and moderately reactive element plays important roles in both industrial and biological systems. In nature it is primarily found as the mineral sphalerite (ZnS) and is the second most abundant trace element in the human body after iron. Chemically it predominantly forms stable compounds in the +2 oxidation state.

Discovery

Historically zinc was used in India as early as 1000 BCE in brass production. In Europe it was first obtained in metallic form during the 16th century. In 1746 Andreas Marggraf is recognized as the first person to isolate zinc in pure form. This discovery enabled the systematic study of zinc’s chemical properties and marked a turning point in its scientific classification.

Classification and Fundamental Properties

Zinc is located in period 4 and group 12 of the periodic table. Although not classified as a transition metal it is considered a d-block element. Its atomic mass is 65.38 g/mol and its electron configuration is [Ar] 3d¹⁰ 4s². At room temperature zinc is a solid and predominantly forms compounds as the Zn²⁺ ion. These characteristics give it a distinct profile both physically and chemically.

Physical and Chemical Properties

Zinc is a brittle bluish-white metal with a melting point of 419.5 °C and a boiling point of 907 °C. Its density is 7.14 g/cm³. It has moderate electrical conductivity. Zinc is soluble in acidic environments and forms a protective layer of zinc oxide (ZnO) on its surface under atmospheric conditions. This layer provides resistance to corrosion.

Electronegativity and Reactivity

The electronegativity of zinc is 1.65 on the Pauling scale. It exhibits moderate reactivity particularly reacting with acids to release hydrogen gas. It can form complex compounds with alkaline solutions. Its stability under atmospheric conditions is due to the protective ZnO layer. These properties make zinc preferred in both industrial and biochemical processes.

Isotopes

Zinc has five stable isotopes found in nature: ⁶⁴Zn ⁶⁶Zn ⁶⁷Zn ⁶⁸Zn and ⁷⁰Zn. Among these ⁶⁴Zn is the most abundant. Several radioactive isotopes notably ⁶⁵Zn are used in biological tracing and research. The isotopic diversity enables applications of zinc in nuclear and biomedicine fields.

Natural Occurrence and Compounds

Zinc occurs naturally primarily as the mineral sphalerite. Other common compounds include smithsonite (ZnCO₃) hemimorphite (Zn₄Si₂O₇(OH)₂·H₂O) and zinc oxide (ZnO). Zinc is extracted from these minerals using pyrometallurgical and hydrometallurgical methods. Zinc deposits rich in natural reserves form the primary sources for industrial production.

Biological Role and Importance to Living Organisms

Zinc is present in the human body in amounts of approximately 1.5–2.5 grams and is the second most abundant trace element after iron. It is a structural component of over 300 enzymes and plays critical roles in cell division gene transcription immune function reproduction and neurological processes. Deficiency can lead to symptoms such as growth retardation immune weakness skin disorders and loss of taste and smell. Excess zinc can cause toxic effects. Zinc also contributes to antioxidant defense systems helping prevent cellular damage.

Applications

In industry zinc is primarily used in galvanization processes to protect iron and steel surfaces from corrosion. It is also used in the production of alloys such as brass in battery technologies (especially zinc-carbon and zinc-air batteries) and as zinc oxide in paints plastic additives sunscreens and dermatological products. The conductivity and protective properties of zinc are also utilized in the electrical and hardware industries.