Characteristic

Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic.

Phase at STP solid

Melting point 494 K (221 °C, 430 °F)

Boiling point 958 K (685 °C, 1265 °F)

Density (near r.t.) gray: 4.81 g/cm³

                             alpha: 4.39 g/cm³

vitreous: 4.28 g/cm3

when liquid (at m.p.) 3.99 g/cm³

Critical point 1766 K, 27.2 MPa

Heat of fusion gray: 6.69 kJ/mol

Heat of vaporization 95.48 kJ/mol

Molar heat capacity 25.363 J/(mol·K)

Application

The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells. Applications in electronics, once important, have been mostly replaced with silicon semiconductor devices. Selenium is still used in a few types of DC power surge protectors and one type of fluorescent quantum dot.

Selenium_MSDS.pdf