Gallium is a soft metal whose compounds are especially important in electronics. Gallium arsenide and gallium nitride are semiconductors used in light-emitting and other electronic devices. These compound materials show that useful electronic behavior extends beyond elemental silicon and depends on the combination of elements.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
How does a gallium-nitride-based LED convert electrical input into light?
Gallium nitride semiconductor compounds
FOLLOW THIS RELATIONSHIP
Build the semiconductor region
Gallium and nitrogen form a compound semiconductor incorporated into a fabricated LED, whose active regions and electrical contacts control the flow of charge.
Explore the model (optional)
GaFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Atomic identity, reference properties and structure models
INTERACTIVE 3D31 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Ar] 3d10 4s2 4p1. 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.
Lecoq de Boisbaudran detected gallium through an unfamiliar line in zinc-derived material in 1875. Mendeleev had predicted an element below aluminum with corresponding properties. Isolating the metal allowed prediction and measurement to be compared. The episode linked spectroscopy, separation, and periodic reasoning: a small signal in a mixed material could test a much broader organizing idea.
Before 1875
Missing element predicted
Mendeleev predicted an element occupying the position below aluminum.
1875
Gallium identified and isolated
Lecoq de Boisbaudran detected the spectral evidence and prepared the new metal.
Gallium occurs in small amounts in materials including bauxite, sphalerite, and some coals. Its dispersed occurrence means that it commonly accompanies sources associated with other elements. The element must be separated from this surrounding material before it can enter the high-purity compounds used in electronic devices.
Gallium melts at a temperature close to ordinary room conditions and can remain liquid when cooled below its usual freezing point. It also expands on solidification. These behaviors make changes especially relevant to the metal, while gallium's compounds have electronic properties that require separate consideration.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
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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
302.91 K
at standard pressure unless noted
Boiling point in K
2673 K
101.325 kPa
Density in g/cm³
5.91 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
1.81 Pauling
Pauling scale
First ionization energy in kJ/mol
578.8 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
122 pm
single-bond covalent radius
Common oxidation states
+3
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
19 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1875 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 4
Ga 1.81 Pauling · Gallium
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 13
Ga 1.81 Pauling · Gallium
Electronegativity down group 13. Exact values.
B
2.04
Al
1.61
Ga
1.81
In
1.78
Tl
1.62
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.
