Aluminium (Al)
Aluminium is the 13th element, a post-transition metal in the p-block. Its standard atomic weight is 26.982.
Aluminium
26.982
What the table records
- Atomic number
- 13
- Standard atomic weight
- 26.982
- Group
- 13
- Period
- 3
- Block
- p-block
- Category
- Post-transition metal
- [Ne] 3s2 3p1
- Valence electrons
- 3
- Typical valence
- 3
- Van der Waals radius
- 2.1 Å
- Covalent radius
- 1.21 Å
Molecules containing aluminium
The lightest named structures in this library that contain Al.
Aluminum
Al · 26.98 g/mol
Aluminum Cation
Al+3 · 26.98 g/mol
Aluminate(1-), tetrahydro-, (T-4)-
H₄Al- · 31.01 g/mol
Lithium aluminum hydride
H₄AlLi · 37.96 g/mol
Dimethylalumanylium
C₂H₆Al+ · 57.05 g/mol
Trimethylaluminum
C₃H₉Al · 72.09 g/mol
Diethylalumanylium
C₄H₁₀Al+ · 85.11 g/mol
Dimethylaluminum methylamide
C₃H₁₀AlN · 87.1 g/mol
(2-Methylpropan-2-yl)oxyaluminum(2+)
C₄H₉AlO+2 · 100.1 g/mol
2-Methoxyethoxyaluminum(2+)
C₃H₇AlO₂+2 · 102.07 g/mol
Di(propan-2-yl)alumanylium
C₆H₁₄Al+ · 113.16 g/mol
Triethylaluminum
C₆H₁₅Al · 114.17 g/mol
How to read these numbers
The standard atomic weight is an average over the isotopes as they occur naturally, which is why it is rarely a whole number. It is the figure a molar mass calculation uses. Work in mass spectrometry wants the monoisotopic mass of a single isotope instead, which is a different number.
The two radii are not the same measurement. The covalent radius is half the distance between two bonded atoms of the element; the van der Waals radius is how close a non-bonded atom gets before repulsion takes over, and is always the larger. Space-filling models are drawn with the second, ball-and-stick models with the first — which is why the same molecule looks so different in the two.