Periodic table › Gallium
1. Identity and classification
Soft, ductile, silvery-white metallic solid with relatively low melting point compared to d-block transition metals
- Name and symbol
- Gallium (Gallium) · Ga
- Atomic number
- 31
- Relative atomic weight / mass number
- 69.723 ± 0.001
- Group · period · block
- 13 · 4 · p
- Category
- Post-transition Metal
- State near room temperature
- Solid
- Stable isotopes
- At least one stable isotope
- CAS number
- 7440-55-3
Square brackets [A] indicate a representative isotope mass number, not an average atomic weight. Neutron counts differ between isotopes.
2. Atomic structure and electron configuration
- Protons · electrons in a neutral atom
- 31 · 31
- Neutrons in reference isotope
- 38 (69Ga)
- Full electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹- Abbreviated configuration
[Ar]4s² 3d¹⁰ 4p¹- Electrons per shell
- 2, 8, 18, 3
- Listed oxidation states
- +3
- Electronegativity
- 1.81 (Pauling)
- First ionization energy
- 578.816 kJ/mol · 5.999 eV
- Electron affinity
- 28.946 kJ/mol
- Covalent radius
- 122 pm
- van der Waals radius
- 187 pm
Configurations of superheavy elements may include theoretical predictions. Different definitions of atomic radius are not interchangeable.
3. Physical and thermal properties
- Density
- 5.91 g/cm³
- Melting point
- 302.91 K · 29.76 °C · 85.568 °F
- Boiling point
- 2477 K · 2203.85 °C · 3998.93 °F
- Crystal structure
- Orthorhombic
- Specific heat
- 0.371 J/(g·K)
- Thermal conductivity
- 40.6 W/(m·K)
- Enthalpy of fusion
- 5.59 kJ/mol
- Enthalpy of vaporization
- 254 kJ/mol
- Magnetic ordering
- Diamagnetic
- Mohs hardness
- 1.5
- Speed of sound
- 2740 m/s
Density and structure depend on temperature, pressure and allotrope. 25°C is a room-temperature reference, not STP. Unestablished values are not zero.
4. Chemical behavior and compounds
The listed electron configuration and oxidation states describe atomic structure; compound properties depend on bonding and composition.
Selected compounds: GaO / Ga₂O₃ (Oxide) · GaClₙ (Chloride) · GaFₙ (Fluoride)
Reaction reference
Oxidation behavior depends on temperature, surface passivation and the chemical environment.
Direct reaction with water is element- and condition-dependent.
5. Isotopes
| Isotope | Status | Natural abundance | Half-life |
|---|---|---|---|
| 69Ga | Stable | 60.108% | Stable |
| 70Ga | Radioactive | — | 21.14 m |
| 71Ga | Stable | 39.892% | Stable |
Half-life units: s seconds, m minutes, h hours, d days, Y years. A dash means no natural-abundance value is given, not zero. Listed records are selected ground states; metastable states are distinct.
6. Discovery and occurrence
- Discovery
- 1875 CE
- Scientists associated with discovery
- Paul-Émile Lecoq de Boisbaudran
- Location
- France (Paris)
- Origin
- Natural
- Listed crustal abundance
- Not established
Minerals and naming reference
Trace in Bauxite and Sphalerite (ZnS) ores
Named from scientific/historical roots associated with Gallium (Ga), discovered or characterized by Paul-Émile Lecoq de Boisbaudran.
7. Applications
Gallium Nitride (GaN) blue/white LEDs and fast chargers, Gallium Arsenide (GaAs) 5G/satellite solar cells, non-toxic Galinstan thermometers
Detailed applications by field
- everyday
- Gallium Nitride (GaN) blue/white LEDs and fast chargers, Gallium Arsenide (GaAs) 5G/satellite solar cells, non-toxic Galinstan thermometers
- industry
- Used in post-transition metal processing, specialized alloys, and chemical manufacturing (Gallium Nitride (GaN) blue/white LEDs and fast chargers, Gallium Arsenide (GaAs) 5G/satellite solar cells, non-toxic Galinstan thermometers).
- electronics
- Applied in electronic components, semiconductors, or functional coatings where Gallium's electronic structure ([Ar] 3d¹⁰ 4s² 4p¹) provides target conductivity.
- medicine
- Diagnostic imaging, biomedical instrumentation, or pharmaceutical synthesis research.
- energy
- Utilized in power generation, battery materials, catalysts, or nuclear technology involving Gallium.
- aerospace
- High-performance materials, structural alloys, or space instrumentation utilizing Gallium.
- agriculture
- Soil geochemistry analysis, trace micronutrient research, or analytical environmental monitoring.
- science
- Spectroscopic standard, crystallography, and quantum chemistry studies of Period 4 p-block elements.
8. Biological role and safety
Hazard depends on the isotope, chemical form, dose and exposure route.
Elemental substances, ions, compounds and radioisotopes can have different health effects. This is an educational reference; laboratory work requires the material safety data sheet and trained supervision.
Biological role reference
Classified as non-essential in human and biological systems.