Origin / Meaning of the name Selenium
The name originates from the Greek Selene, who was the Greek goddess of the moon because the element is chemically found with tellurium (Tellus - the Roman goddess of the earth).

Periodic Table Group and Classification of the of the Selenium Element
Elements can be classified based on their physical states (States of Matter) e.g. gas, solid or liquid. This element is a solid. Selenium is classified as an element in the 'Non-Metals' section which can be located in groups 14,15 and 16 of the Periodic Table. Non-metallic elements exist, at room temperature, in two of the three states of matter: gases (Oxygen, Hydrogen & Nitrogen) and solids (Carbon, Phosphorus, Sulfur and Selenium).

Facts about the Discovery and History of the Selenium Element
Selenium was discovered by Jons Jacob Berzelius in 1817

History of the Periodic Table
Check out the brief History of the Periodic Table which details dates and the names of famous scientists and chemists who contributed to the development of the Periodic Table.

Occurrence of the Selenium Element
Occurs as selenide in many sulfide ores
Obtained primarily as a by-product of electrolytic copper refining

Abundances of the element in different environments
% in Universe 3×10^-6%
% in Sun N/A
% in Meteorites 0.0013%
% in Earth's Crust 5×10^-6%
% in Oceans 4.5×10^-8%
% in Humans 5×10^-6%

Associated Uses of Selenium
TV cameras
Xerography
Photographic equipment

The Properties of the Selenium Element
Name of Element : Selenium
Symbol of Element : Se
Atomic Number of Selenium : 34
Atomic Mass: 78.96 amu
Melting Point: 217.0 °C - 490.15 °K
Boiling Point: 684.9 °C - 958.05005 °K
Number of Protons/Electrons in Selenium : 34
Number of Neutrons in Selenium : 45
Crystal Structure: Hexagonal
Density @ 293 K: 4.79 g/cm3
Color of Selenium : gray, red & black

Selenium as on the Periodic Table
Check out Selenium on the Periodic Table which arranges each chemical element according to its atomic number, as based on the Periodic Law, so that chemical elements with similar properties are in the same column. Our Periodic Table is simple to use - just click on the symbol for Selenium as on the Periodic Table for additional information and for an instant comparison of the Atomic Weight, Melting Point, Boiling Point and Mass - G/cc with any other element. An invaluable source of facts and information as a Chemistry reference guide.

Other elements classified as non-metals
The other elements contained in this classification are as follows:

• Hydrogen
• Carbon
• Nitrogen
• Oxygen
• Phosphorus
• Sulfur

What is Selenium - IUPAC and the Modern Standardised Periodic Table
The Standardised Periodic Table in use today was agreed by the International Union of Pure Applied Chemistry, IUPAC, in 1985 and now recognises more periods and elements than Dimitri  Mendeleev knew in his day in his day but still all fitting into his concept of  the "Periodic Table" in which Selenium is just one element that can be found.

Learn about what is Selenium with these fast facts...
These articles contain facts and information relating to Selenium and each of the other elements including the Periodic Symbol,  group, classification, properties and atomic number which is often referred to as the Periodic Table Number. Test your knowledge of chemistry and the Periodic Table by completing the Element Symbols and Atomic Numbers on our Blank Periodic Table. Chemistry students will also find a helpful section on Chemical Formulas.