Selenium

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 its periodic table neighbors, sulfur and tellurium.

Properties of Selenium

• Physical State: Selenium is a solid at room temperature.
• Color: It exists in several allotropes, but the most stable form is a gray, metallic-looking solid.
• Odor: Elemental selenium has no characteristic odor.
• Conductivity: It is a semiconductor, meaning it has electrical conductivity between that of a conductor and an insulator.
• Chemical Reactivity: Selenium is less reactive than sulfur and tellurium, but still reacts with many elements and compounds.

Uses of Selenium

Selenium has several important uses:

• It is used in glassmaking to decolorize glass and remove greenish tints.
• It is an essential micronutrient for many organisms, including humans, and is important for maintaining good health.
• It is used in electronics and photocopiers due to its photoconductivity.
• It is used in some types of solar cells.

Chemical Compounds of Selenium

Selenium forms a variety of chemical compounds, including selenides, selenates, and selenites. These compounds have diverse applications in industry and research.

Environmental Significance

Selenium can be both beneficial and harmful to the environment. In small amounts, it is necessary for life, but in larger amounts, it can be toxic to many organisms, including humans. Selenium pollution can occur from industrial activities such as mining and smelting.

Study Guide

When studying selenium, it is important to understand its chemical properties, its uses in industry and biology, and its environmental impact. Pay particular attention to the following topics:

1. The electronic configuration and position of selenium in the periodic table.
2. The allotropes of selenium and their properties.
3. The role of selenium in biological systems and its significance as a micronutrient.
4. The applications of selenium in industry, such as in glassmaking and electronics.
5. The environmental impact of selenium and measures to mitigate its pollution.

Understanding these aspects will give you a comprehensive understanding of the element selenium.