Aluminum Facts – Atomic Number 13 or Al 1

Aluminum is the 13th element of the periodic table. These aluminum facts contain chemical and physical data along with general information and history.

Element cell for Aluminum
Aluminum periodic table cell

Basic Aluminum Facts

Name: Aluminum

Atomic Number: 13

Element Symbol: Al

Group: 13

Period: 3

Block: p

Element Family: Basic Metal

Atomic Mass: 26.981 5385(7)

Electron Configuration: [Ne]3s23p1 (shorthand) or 1s22s22p63s23p(full)

Discovery: Hans Christian Ørsted in 1807.

Alum was a commonly known substance since ancient times. Today, we know alum is potassium aluminum oxide. Around 1750, German scientist Andreas Marggraf separated a new metallic substance from alum and named the substance alumina. Alumina is aluminum oxide. Unfortunately for Marggraf, he could not separate aluminum from alumina. Sir Humphrey Davy came close with his electrolysis equipment in 1807, but his metal was a mixture of aluminum and iron. It wasn’t until Swedish chemist Hans Christian Ørsted isolated pure aluminum in 1825.

Name Origin: Sir Humphrey Davy coined the term aluminium to give the element suffix of -ium to alumina.

Spelling: In 1990, the IUPAC designated the spelling ‘aluminium’ as the official name of the 13th element. Three years later, they allowed the US spelling ‘aluminum’ as an acceptable variant.


Natural aluminum is comprised of two isotopes: 26Al and 27Al. Twenty radioactive isotopes have been produced under laboratory conditions ranging from 21Al to 42Al.

Aluminum-26 is a radioactive isotope containing 13 neutrons. Aluminum-26 decays by β+ decay into magnesium-26 with a half-life of 717,240 years. Only trace amounts of aluminum-26 appear in nature.

Aluminum-25 is the only stable isotope of aluminum and contains 14 neutrons. 100% of natural aluminum is aluminum-25.

Aluminium Chunk
Small chunk of aluminum metal. Credit: Creative Commons

Physical Data

Density: 2.70 g/cm3

Melting Point: 933.47 K ​(660.32 °C, ​1220.58 °F)

Boiling Point: 2743 K ​(2470 °C, ​4478 °F)

State at 20ºC: Solid

Heat of Fusion: 10.71 kJ/mol

Heat of Vaporization: 284 kJ/mol

Molar Heat Capacity: 24.20 J/mol·K

Aluminum Atom
Electron shell configuration of an aluminum atom.

Atomic Data

Atomic Radius: 1.84 Å

Covalent Radius: 1.21 Å

Van der Waals Radius:  1.84 Å

Electron Affinity: 41.762

Electronegativity: 1.61

1st Ionization Energy: 577.539 kJ/mol

2nd Ionization Energy: 1816.679 kJ/mol

3rd Ionization Energy: 2744.781 kJ/mol

4th Ionization Energy: 11577.469 kJ/mol

5th Ionization Energy: 14841.857 kJ/mol

6th Ionization Energy: 18379.49 kJ/mol

7th Ionization Energy: 23326.3 kJ/mol

8th Ionization Energy: 27465.52 kJ/mol

Oxidation States: +3 (common), +2, +1 (uncommon)

Fun Aluminum Facts

  • Aluminum is a soft silver lusterous solid at room temperature.
  • Aluminum was once known as the Metal of Kings. It was extremely difficult to produce in quantity for the first few decades after it was discovered. Aluminum metal was more valuable than gold and used for decorative applications.
  • The Hall-Héroult process to refine aluminum with electricity was developed in 1888. This greatly reduced the price of aluminum metal and is still used today.
  • Recycling aluminum metal takes only 5% of the energy required to produce aluminum from bauxite ore. Recycle those aluminum cans!
  • Aluminum accounts for 8% of the Earth’s crust and is the third most abundant element. Aluminum is the most common metal in the Earth’s crust.
  • Aluminum is paramagnetic and a good electrical conductor.
  • Aluminum replaced silver as a backing for mirrors. Silver is evaporated at low pressure and attached to a substrate surface to make the reflective surface of the mirror.
  • Aluminum is considered non-toxic to humans, but a link has been suggested between aluminum and Alzheimer’s disease. This link has not been proven.
  • Aluminum metal is relatively soft, but adding aluminum to copper, magnesium or zinc greatly increases its strength while reducing its weight.
  • Aluminum metal has no aroma, making it useful for food preparation and storage.

Learn more about elements on the periodic table.