Cd 48
Cadmium was first discovered in 1817 by the German chemist Friedrich Stromeyer, who isolated it from a sample of zinc carbonate. While investigating ores of zinc, he noticed unusual impurities which he surmised were a new element. The name 'cadmium' is derived from the Latin word 'cadmia,' which refers to calamine, the mineral from which cadmium can be extracted. In the mid-19th century, cadmium became used more widely in pigment manufacturing. By the 1900s, its electroplating properties gained significant industrial interest, leading to its introduction in battery production and other applications. Over the decades, the understanding of cadmium's toxicity has evolved, leading to stricter regulations surrounding its use.
Cadmium occurs in nature mainly in combination with other elements. It is primarily found within the Earth's crust, where it occurs at an average concentration of about 0.1 parts per million. Cadmium is often associated with zinc ores and can also be found in minerals such as greenockite (cadmium sulfide). Its natural extraction occurs primarily in regions rich in zinc deposits, where cadmium is retrieved as a by-product of zinc production. As a transition metal, cadmium is not found freely in nature due to its reactive properties but is instead extracted through industrial processes from ore mining.
Cadmium has no known essential biological function in humans and is considered a toxic element. However, among certain organisms, like some microorganisms and plants, cadmium can play a role in biochemical processes, although it is generally regarded as harmful. In humans, cadmium exposure can lead to various health issues, including kidney damage, bone fragility, and respiratory problems. Due to its toxicity, its occupational exposure is strictly regulated in many countries, highlighting the importance of monitoring cadmium levels to protect health and ensure safety.
Cadmium is a soft metal with a melting point of 321.1 °C and a boiling point of 767 °C. It has a low density of approximately 8.65 g/cm³ and exhibits a metallic luster. Chemically, cadmium is reactive, showing affinity for oxygen and sulfur, forming compounds such as cadmium oxide and cadmium sulfide. It undergoes oxidation easily, producing cadmium(II) compounds when exposed to air. Cadmium does not dissolve in pure water but can be leached from materials in the presence of acids, making its chemical behavior significant in both industrial processes and environmental contexts.
Cadmium is predominantly utilized in the production of batteries, specifically nickel-cadmium (NiCd) batteries, which are known for their rechargeable capabilities. Additionally, cadmium is employed in electroplating due to its resistance to corrosion and wear, providing protection for various metals. It is also used in pigments, such as cadmium yellow, and in the manufacturing of certain types of solar panels and semiconductors. Furthermore, cadmium's unique properties have made it useful in the production of alloys and in certain chemical processes, although its usage is closely monitored due to environmental and health concerns.