Group 12 element

Zinc symbol (fixed width)

Mercury symbol

Sphalerite4

Group 12 elements consist of four chemical elements in the periodic table: zinc (Zn), cadmium (Cd), mercury (Hg), and the unconfirmed synthetic element copernicium (Cn), with atomic numbers 30, 48, 80, and 112 respectively. These elements are often not considered typical transition metals, due to their unique properties, including having a relatively low melting point for metals and being less chemically reactive than other transition metals. They are located in the d-block of the periodic table and share some similarities in their physical and chemical properties.

Properties

Group 12 elements exhibit a range of physical and chemical properties but share some common characteristics. Zinc, cadmium, and mercury are known for their relatively low melting and boiling points compared to most other metals. Mercury is unique among metals for being liquid at room temperature. These elements typically form divalent cations (Zn^2+, Cd^2+, Hg^2+), which contribute to their chemical behavior and compound formation.

Chemical

Chemically, Group 12 elements tend to be less reactive than their neighboring transition metals. Zinc is somewhat reactive, reacting with acids to release hydrogen gas and forming zinc compounds with various nonmetals. Cadmium and mercury are less reactive but can still form a variety of compounds, including those with oxygen, sulfur, and halogens.

Physical

Physically, these elements have metallic characteristics, including luster and electrical conductivity. Zinc and cadmium have a solid state at room temperature, with zinc being somewhat hard and brittle, while cadmium is softer. Mercury's liquid state at room temperature is one of its most notable physical properties, making it unique among the elements.

Uses

Group 12 elements have diverse applications in various industries. Zinc is widely used for galvanizing to protect iron and steel from corrosion, in alloys such as brass, and in batteries. Cadmium finds use in rechargeable nickel-cadmium batteries, as pigments, and for corrosion-resistant plating on metals. Mercury has historically been used in thermometers, barometers, and other scientific instruments, although its use has declined due to toxicity concerns. Copernicium, being synthetic and highly radioactive, has no practical applications and is used only in scientific research.

Health and Environmental Concerns

Cadmium and mercury are toxic elements, posing significant health and environmental risks. Cadmium exposure can lead to kidney damage and bone diseases, while mercury exposure can affect the nervous system and kidneys. Both elements can accumulate in the environment, leading to contamination of water sources and the food chain. Zinc is less toxic but can still pose risks in large amounts. The toxicity of copernicium has not been studied, given its short half-life and the minute amounts produced.

Discovery and History

Zinc has been used since ancient times, with evidence of its use in alloys dating back to 1000 BC. Cadmium was discovered in 1817 by Friedrich Stromeyer as an impurity in zinc ores. Mercury has been known since antiquity, with its use dating back to ancient civilizations for various purposes, including in medicines and cosmetics. Copernicium was discovered in 1996 by scientists at the GSI Helmholtz Centre for Heavy Ion Research in Germany.

Conclusion

Group 12 elements play significant roles in modern industry and technology, despite the health and environmental concerns associated with some of these elements. Their unique properties and applications make them an interesting subject of study in the field of chemistry.

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