Selenium is a chemical element; it has symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth's crust.

Selenium is a chemical element with symbol Se and atomic number 34. Classified as a nonmetal, Selenium is a solid at room temperature.

2023年11月25日 · Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between the elements above and below on the periodic table, sulfur and tellurium. People most often encounter selenium as a nutritional supplement or in dandruff shampoo.

2025年3月20日 · selenium (Se), a chemical element in the oxygen group (Group 16 [VIa] of the periodic table), closely allied in chemical and physical properties with the elements sulfur and tellurium. Selenium is rare, composing approximately 90 parts per billion of the crust of Earth.

Selenium is a chemical element. Its chemical symbol is Se and its atomic number is 34. It has 34 protons and 34 electrons and a mass number of 78.96. Selenium (selenium atoms only) has several different forms. They are called allotropes. The most stable of these is a dense gray semimetal (an element that is partially a metal and a nonmetal).

Selenium (pronounced as si-LEE-nee-em) is a metalloid, existing in both amorphous and crystalline forms, where the former appears as red/black powder and the latter as a silver-gray rock [1]. Denoted by the chemical symbol Se, it has 24 isotopes of which only six exist naturally in different concentrations in the earth’s crust [4].

2023年5月4日 · Selenium is a metallic element with the atomic number 34 and is represented by the symbol ‘Se’ in the periodic table. It is classified as a nonmetal and belongs to the p-block of group 16 of the periodic table. It has five allotropic forms that are classified in three groups as red Se, gray Se, and black Se.

Selenium is a member of the chalcogen family. The chalcogens are elements in Group 16 (VIA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. Other chalcogens are oxygen, sulfur, tellurium, and polonium. The name chalcogen comes from the Greek word chatkos, meaning "ore."

Selenium has both a photovoltaic action (converts light to electricity) and a photoconductive action (electrical resistance decreases with increased illumination). Selenium is therefore useful in photocells and solar cells. It can also convert a.c. electricity to d.c. electricity, so is extensively used in rectifiers.

2020年11月21日 · The chemical symbol for Selenium is Se. Selenium is a nonmetal with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic.