Elements
34

Se

Selenium

Selenium (Se) is a grey non metal that can also exist as a red allotrope. It has the atomic number 34 in the periodic table. It is located in Group 16 of the periodic table. It has the symbol Se.

Selenium is a non metal, sometimes considered a metalloid, rarely occurring in its elemental state on earth but mainly in the earth’s crust in sulfide ores. Industrially, Selenium is obtained as a byproduct of the refining sulfide ores but is usually produced in an ore, not as a pure substance. It is commonly used in glassmaking and pigments. It also has some use as a semi-conductor and electronics due to its ability to conduct a current. Selenium was discovered by Jöns Jakob Berzelius and Johan Gottlieb Gahn. Both scientists owned a factory producing Sulphuric acid from which a red precipitate was created. When burned the red substance gave off a strange smell which they first thought was Tellurium. It was not until 1818 when Alexander Marcet analysed the red precipitate identifying the element Selenium. It is located in Group 16 and it has a melting point of 221°c and a boiling point of 685°c being a solid at room temperature.

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FAQ's

What is the Melting Point for Selenium?

Selenium has a Melting Point of 217°F, meaning at 217°F it will turn to a liquid.

What is the Boiling Point for Selenium?

Selenium has a Boiling Point of 684.9°F, meaning at 684.9°F it will turn to a Gas.

What is the Electronegativity of Selenium?

Selenium's Electronegativty is 2.55. Electronegativity is a measure of how strongly atoms attract bonding electrons to themselves.

What is the Heat of Vaporization of Selenium?

Selenium has a Heat of Vaporization of 37.7 kJ/mol.

Uses

Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers. Also colors glass red.

Sources

Obtained from lead, copper and nickel refining. Conducts electricity when struck by light.

34
Protons
34
Electrons
45
Neutrons

Se

Element Symbol
Se
Atomic Weight
78.971
Atomic Number
34
State
Solid
Melting Point
Unknown
217
°C
Boiling Point
684.9
Unknown
°C
Heat of Vaporization
37.7
Unknown
kJ/mol
Crystal Structure
Hexagonal
Thermoconductivity
0.0204
Unknown
W/cmK
Shells
2,8,18,6
Group
Non-Metal
Period
4
Block
P Block
Orbitals
[Ar] 3d10 4s2 4p4
Coefficient of Thermal Expansion
45.0 10^-6 K^-1
Covalent Radius
1.16 Å
Density at 293K
4.79 g/cm³
Electrical Conductivity
1.0e-12 10^6/cm ohm
First Ionization Potential
9.7524 V
Second Ionization Potential
21.19 V
Third Ionization Potential
30.82 V
Ionic Radius
.50 (+4) Å
Oxydation States
'-2,(4),6
Lattice Parameter
4.3658 Å
Lattice Parameter 2
--
Lattice Parameter 3
--
Pronounced

si-LEE-ni-em

Discovered by

Jöns Berzelius

Discovery date

1817

Orbital configuration
2,8,18,6

Download the Periodic Table

Explore Other Non-Metals

1.008
1

H

Hydrogen
32.06
16

S

Sulphur
12.011
6

C

Carbon
14.007
7

N

Nitrogen
15.999
8

O

Oxygen
30.974
15

P

Phosphorus
Non-metals are the substances that do not exhibit such characteristic of metals as hardness, mechanical adaptability or the ability to conduct electricity. This series contains a few non-metals located in different groups of the periodic table: hydrogen (H), carbon (C), nitrogen (N), phosphorus (P), oxygen (O), sulfur (S) and selenium (Se).
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