Selenium (Se) – Periodic Table [Element Information & More]

Selenium element (Se) is in group 16 and period 4 of a periodic table. Selenium is in the p-block and it is classified as a carbon group element (chalcogens) on the periodic table.

There is a lot more information related to selenium which is mentioned in the Information Table given below.

So let’s dive right into it!

Table of contents

• Selenium element (Information Table)
• Selenium element in Periodic table
• Facts about Selenium
• Properties of Selenium
• Uses of Selenium

Selenium Element (Information Table)

The important data related to selenium element is given in the table below.

Appearance of selenium	Hexagonal selenium has Metallic gray color Monoclinic selenium has Deep red color
Atomic number of selenium	34
Symbol of selenium	Se
Atomic mass of selenium	78.971 u
Protons, Neutrons & Electrons in selenium	Protons: 34, Neutrons: 45, Electrons: 34
State of selenium (at STP)	Solid
Group number of selenium in periodic table	16
Period number of selenium in periodic table	4
Block of selenium in periodic table	p-block
Category of selenium	Nonmetals (Chalcogens)
Bohr model or Electrons per shell or Electrons arrangement in selenium	2, 8, 18, 6
Electron configuration of selenium	[Ar] 3d10 4s2 4p4
Orbital diagram of selenium
Valence electrons in selenium	6
Electronegativity of selenium (on pauling scale)	2.55
Atomic radius of selenium (van der Waals radius)	190 picometers
Density of selenium	4.82 g/cm3
1st ionization energy of selenium	9.752 eV
Main isotope of selenium	80Se
Melting point of selenium	494 K or 221 °C or 430 °F
Boiling point of selenium	958 K or 685 °C or 1265 °F
Crystal structure of selenium	Hexagonal
Discovery of selenium	By Jöns Jakob Berzelius and Johann Gottlieb Gahn (in 1817)

Also see: Interactive Periodic Table (It has rotating bohr models as well as many other details of all the 118 elements in a single periodic table).

Selenium element in Periodic table

The Selenium element (Se) has the atomic number 34 and is located in group 16 and period 4. Selenium is a nonmetal and it is classified as a chalcogen element.

Facts about selenium

Here are a few interesting facts about selenium element.

1. The name selenium came from the Greek word “Selene”, which means moon.
2. Selenium was discovered by Jöns Jakob Berzelius and Johann Gottlieb Gahn in 1817.
3. Selenium has different colors as well as different crystal structures.
4. The monoclinic selenium has deep red color while the hexagonal selenium has metallic gray color.
5. The annual production of selenium in the entire world is around 2000 tons.
6. The majority of selenium (around 50% of the total production) is used in the manufacturing of glass.

Properties of selenium

Here is a list of some physical properties and chemical properties of selenium.

Physical properties of selenium

• Selenium is a nonmetal and it has different crystal structures (depending on the temperatures). The monoclinic selenium has brick red color while the hexagonal selenium has metallic gray color.
• Selenium behaves like a semiconductor and hence it is used in photocells.
• Selenium has many isotopes, out of which ⁸⁰Se is the most abundant.

Chemical properties of selenium

• Selenium reacts with oxygen to form two oxides (SeO₂ and SeO₃).
• Selenium reacts with halogens like fluorine, chlorine and bromine to form respective selenium halides.
• Selenium reacts with cyanides to form selenocyanates.

Uses of selenium

Here are some uses of the selenium element.

• The major use of selenium (around 50% of total production) is in manufacturing of glass.
• Selenium is also used in making pigments.
• Selenium has the properties of a semiconductor and hence it is also used in photocells.
• Selenium is also used with bismuth in making brasses.
• Selenium is used in copper alloys to improve the machinability of copper alloys.

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