Periodic table / Selenium

Overview

Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. It rarely occurs in its elemental state in nature, or as pure ore compounds.

Electron configuration

The electron configuration of Selenium is [Ar] 3d10 4s2 4p4, with electron shells of 2, 8, 18, 6.

Physical and chemical properties

Selenium is classified as a nonmetal. It has an atomic mass of 78.972 and exists as a solid at standard conditions, appearing as black, red, and gray (not pictured) allotropes.

Real-world uses of Selenium

Selenium plays an important role in chemistry and biology, and is used in industrial processes, manufacturing, or as a key component of compounds essential to life.

Interesting facts about Selenium

• Selenium has the atomic number 34 and chemical symbol Se.
• It belongs to period 4, group 16 of the periodic table.
• Selenium was discovered by Jöns Jakob Berzelius.

Explore Selenium interactively

Want to compare Selenium with other elements or see it highlighted on the full table? Open the interactive periodic table and click on Se to explore properties, trends, and neighboring elements. You can also test your knowledge with our periodic table quiz game.