Selenium: An Overview

Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of sulfur and tellurium. Selenium is an essential trace element in the human body, playing a key role in various physiological processes including metabolism and immune function.

Properties of Selenium

Selenium exists in several allotropic forms, but the most stable form is a red amorphous powder. It is a semiconductor and has photovoltaic and photoconductive properties, making it useful in photocopiers, solar cells, and other electronic devices. Selenium also exhibits phototropic and thermotropic properties, meaning its electrical conductivity increases with exposure to light and with rising temperature.

Occurrence and Uses

Selenium is found in metal sulfide ores, and its most common commercial source is as a byproduct of refining copper. It is used in the production of glass, pigments, and as a dietary supplement. Selenium is also a crucial component in some industrial applications, including the production of rubber, plastics, and fungicides.

Biological Importance

Selenium is essential for human health and is incorporated into selenoproteins, which have a diverse range of functions, including antioxidant activity and regulating thyroid hormone metabolism. Selenium deficiency can lead to health issues such as Keshan disease and Kashin-Beck disease, which affect the heart and joints, respectively. However, excessive selenium intake can also be harmful, so maintaining an appropriate balance is crucial.

Study Guide

1. What is the chemical symbol for selenium? Se
2. What role does selenium play in the human body? It is an essential trace element involved in metabolism and immune function.
3. What are some common uses of selenium? It is used in the production of glass, pigments, electronic devices, and as a dietary supplement.
4. What are the potential health issues associated with selenium deficiency? Keshan disease and Kashin-Beck disease
5. What are selenoproteins, and what are their functions? Selenoproteins are proteins that incorporate selenium into their structure, and they have diverse functions including antioxidant activity and regulating thyroid hormone metabolism.