34 Se Selenium 78.971 u

Selenium

Add one script tag to your page:

<div data-chemfyi="element" data-slug="Se"></div>
<script src="proxy.php?url=https%3A%2F%2Fcdn.jsdelivr.net%2Fnpm%2Fchemfyi-embed%401%2Fdist%2Fembed.min.js" defer></script>

Embed as an iframe:

<iframe src="proxy.php?url=https%3A%2F%2Fchemfyi.com%2Fiframe%2Felement%2FSe%2F%3Fstyle%3Dmodern%26amp%3Btheme%3Dlight" width="420" height="400" frameborder="0" loading="lazy" style="border:0;border-radius:10px;max-width:100%"></iframe>

Paste the URL in WordPress, Medium, or Ghost:

https://chemfyi.com/element/se/

Shields.io-compatible SVG badge:

Selenium badge ![Selenium](https://chemfyi.com/badge/element/Se.svg)

Web Component:

<chemfyi-element slug="Se"></chemfyi-element>
<script src="proxy.php?url=https%3A%2F%2Fcdn.jsdelivr.net%2Fnpm%2Fchemfyi-embed%401%2Fdist%2Fembed.min.js" defer></script>
Period
4
Group
16
Block
p-block
Phase (STP)
Solid

Selenium is an essential trace element for humans in small amounts. It is used in glass, electronics, and solar cells.

Appearance: Black, red, and gray allotropes

Physical Properties

Atomic Mass 78.971 u
Density 4.809 g/cm³
Melting Point 220.9 °C
Boiling Point 684.9 °C
Phase at STP Solid
Atomic Radius 103.0 pm

Electronic Properties

Electronegativity 2.55
Ionization Energy 941.0 eV
Electron Affinity 195.0 eV
Valence Electrons 6

Electron Configuration

Configuration [Ar] 3d¹⁰ 4s² 4p⁴

Electron Shell Configuration

Selenium electron shell configuration Se 2e⁻ 8e⁻ 18e⁻ 6e⁻

Position in Periodic Table

Selenium position in the periodic table Se

Discovery

Discovered by: Jons Jacob Berzelius
Year: 1817

Block & Period

Block

s p d f

Period

1 2 3 4 5 6 7

Periodic Table

Lanthanides Actinides

More Nonmetal

1 H Hydrogen 6 C Carbon 7 N Nitrogen 8 O Oxygen 15 P Phosphorus 16 S Sulfur

Frequently Asked Questions

What is Selenium?
Selenium (Se) is a chemical element with atomic number 34. It is a solid at standard temperature and pressure, classified as a nonmetal.
What are the key properties of Selenium?
Selenium has an atomic mass of 78.971 u, density of 4.809 g/cm³, melting point of 220.9°C, boiling point of 684.9°C.
What is the electron configuration of Selenium?
The electron configuration of Selenium is [Ar] 3d10 4s2 4p4. It is in the p-block of the periodic table.
Who discovered Selenium?
Selenium was discovered by Jons Jacob Berzelius in 1817.
What is the electronegativity of Selenium?
Selenium has an electronegativity of 2.55 on the Pauling scale.