Selenium links illumination to electrical behavior: its conductivity changes with light, and it has been used in photocells and related devices. Selenium compounds also modify glass color. These examples provide two ways to investigate how the same element participates in materials that interact with light.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
How can selenium color or decolourise glass?
Selenium-containing glass formulations
FOLLOW THIS RELATIONSHIP
Specify the glass formulation
Selenium-containing ingredients enter a multicomponent glass, where the surrounding chemistry determines which selenium-containing forms develop during manufacture and influence the finished optical material.
Explore the model (optional)
SeFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Atomic identity, reference properties and structure models
INTERACTIVE 3D34 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Ar] 3d10 4s2 4p4. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
An industrial residue opened a light-sensitive story
Berzelius investigated a deposit from sulfuric-acid manufacture in 1817 and initially suspected tellurium. Further examination established selenium as a different element with related chemistry. Decades later, reports of light-dependent electrical conductivity prompted new experiments. Chemical identification was only a beginning: an already known element could reveal useful physical behavior beyond what its first investigators had understood.
1817
Element identified
Berzelius distinguished selenium while investigating residue from acid manufacture.
1873
Light response reported
Willoughby Smith's report of light-dependent conductivity stimulated published discussion and further experiments.
Selenium occurs in including clausthalite and can be recovered from residues associated with copper processing. Its industrial source can therefore be connected to another metal's stream. This occurrence differs from a pure selenium specimen and requires separation from the other substances present in the source material.
Selenium can adopt several structural forms with different colors and electrical behavior. Its conductivity can increase under illumination, and suitable devices can also turn light into electrical output. These effects help connect changes at the material level with light-detection and imaging technologies built around a complete device.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
494 K
at standard pressure unless noted
Boiling point in K
958 K
101.325 kPa
Density in g/cm³
4.81 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
2.55 Pauling
Pauling scale
First ionization energy in kJ/mol
941 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
120 pm
single-bond covalent radius
Common oxidation states
-2, +4, +6
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
0.05 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1817 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 4
Se 2.55 Pauling · Selenium
Electronegativity across period 4. Exact values.
K
0.82
Ca
1
Sc
1.36
Ti
1.54
V
1.63
Cr
1.66
Mn
1.55
Fe
1.83
Co
1.88
Ni
1.91
Cu
1.9
Zn
1.65
Ga
1.81
Ge
2.01
As
2.18
Se
2.55
Br
2.96
Kr
3
Electronegativity down group 16
Se 2.55 Pauling · Selenium
Electronegativity down group 16. Exact values.
O
3.44
S
2.58
Se
2.55
Te
2.1
Po
2
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
