|Isotope||Atomic mass (Da)||Isotopic abundance (amount fraction)|
Al: 13 - Covalenz radius: 28.0855: Silicon: Si: 14 - Ionization energy: 30.9738: Phosphorus: P: 15: For chemistry students and teachers: The tabular chart on the right is arranged by Atomic mass (weight). The lightest chemical element is Hydrogen and the heaviest is Hassium. The unity for atomic mass is gram per mol. In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together. Finding molar mass starts with units of grams per mole (g/mol).
Aluminium is a monoisotopic element and its atomic weight is determined solely by its isotope 27Al. The Commission last revised the standard atomic weight of aluminium in 2017 based on the latest Atomic Mass Evaluation by IUPAP.
26Al is radioactive with a half-life of 0.705(24) Ma, too short for survival of a detectable amountof primordial isotope. However, 26Al is recognized as a spallation product of argon from cosmic rays. In addition,secondary cosmic rays including muons interact with Si-bearing rocks to produce 26Al in measurableamounts, but far below levels that would affect the atomic-weight value in normal materials.
Al Atomic Mass Number
27Al is the most abundant isotope in the earth's crustal rocks with an uneven atomic number.
© IUPAC 2003
Al Atomic Mass Rounded
Al Atomic Mass
Ar(Al) = 26.981 5384(3) since 2017
The name derives from the Latin, alum and alumen for 'stringent' because the early Romans called anysubstance with a stringent taste alum. The element was known in prehistoric times. In 1825, the Danishphysicist, Hans Christian Oersted, isolated impure aluminium. The pure metal was first isolated by theGerman chemist Friedrich Wöhler in 1827.