Periodic table › Aluminium
Aluminium — Al
Post-transition Metal · Group 13 · Period 3
Open the 3D atom, orbital and crystal lab →1. Identity and classification
Soft, ductile, silvery-white metallic solid with relatively low melting point compared to d-block transition metals
- Name and symbol
- Aluminium (Aluminium) · Al
- Atomic number
- 13
- Relative atomic weight / mass number
- 26.982 ± 0.001
- Group · period · block
- 13 · 3 · p
- Category
- Post-transition Metal
- State near room temperature
- Solid
- Stable isotopes
- At least one stable isotope
- CAS number
- 7429-90-5
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
- 13 · 13
- Neutrons in reference isotope
- 14 (27Al)
- Full electron configuration
1s² 2s² 2p⁶ 3s² 3p¹- Abbreviated configuration
[Ne]3s² 3p¹- Electrons per shell
- 2, 8, 3
- Listed oxidation states
- +3
- Electronegativity
- 1.61 (Pauling)
- First ionization energy
- 577.561 kJ/mol · 5.986 eV
- Electron affinity
- 42.55 kJ/mol
- Covalent radius
- 121 pm
- van der Waals radius
- 184 pm
Configurations of superheavy elements may include theoretical predictions. Different definitions of atomic radius are not interchangeable.
3. Physical and thermal properties
- Density
- 2.7 g/cm³
- Melting point
- 933.437 K · 660.287 °C · 1220.517 °F
- Boiling point
- 2792 K · 2518.85 °C · 4565.93 °F
- Crystal structure
- FCC
- Specific heat
- 0.897 J/(g·K)
- Thermal conductivity
- 237 W/(m·K)
- Enthalpy of fusion
- 10.71 kJ/mol
- Enthalpy of vaporization
- 284 kJ/mol
- Magnetic ordering
- Paramagnetic
- Mohs hardness
- 2.75
- Speed of sound
- 5000 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
Aluminium oxide and hydroxide are amphoteric; aluminium reacts with suitable acids and strong bases.
Selected compounds: AlO / Al₂O₃ (Oxide) · AlClₙ (Chloride) · AlFₙ (Fluoride)
Reaction reference
A protective aluminium oxide film forms in air.
The oxide film limits reaction with cold water under ordinary conditions.
5. Isotopes
| Isotope | Status | Natural abundance | Half-life |
|---|---|---|---|
| 27Al | Stable | 100% | Stable |
| 28Al | Radioactive | — | 2.245 m |
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
- Known since antiquity; no exact discovery year
- Scientists associated with discovery
- Known since antiquity
- Location
- Denmark (Copenhagen)
- Origin
- Natural
- Listed crustal abundance
- Not established
Minerals and naming reference
Bauxite (Gibbsite, Boehmite, Diaspore), Cryolite
Named from scientific/historical roots associated with Aluminium (Al), discovered or characterized by Hans Christian Ørsted.
7. Applications
Aircraft structures, beverage cans, kitchen foil, high-voltage overhead power lines, window frames
Detailed applications by field
- everyday
- Aircraft structures, beverage cans, kitchen foil, high-voltage overhead power lines, window frames
- industry
- Used in post-transition metal processing, specialized alloys, and chemical manufacturing (Aircraft structures, beverage cans, kitchen foil, high-voltage overhead power lines, window frames).
- electronics
- Applied in electronic components, semiconductors, or functional coatings where Aluminium's electronic structure ([Ne] 3s² 3p¹) provides target conductivity.
- medicine
- Diagnostic imaging, biomedical instrumentation, or pharmaceutical synthesis research.
- energy
- Utilized in power generation, battery materials, catalysts, or nuclear technology involving Aluminium.
- aerospace
- High-performance materials, structural alloys, or space instrumentation utilizing Aluminium.
- agriculture
- Soil geochemistry analysis, trace micronutrient research, or analytical environmental monitoring.
- science
- Spectroscopic standard, crystallography, and quantum chemistry studies of Period 3 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.