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Aluminium

Element 13 · Post-transition metal

Specimen

Atomic number
13
Atomic mass
26.982
State at room temperature
Solid
Melting point
660.3 °C
Boiling point
2,519 °C
Density
2.7 g/cm³
Discovered
Ancient

Atomic mass from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Allowed in food. The EU allows aluminum metal as color E 173, only on the outside of sugar decorations for cakes. In 2008, EFSA set a tolerable intake of 1 mg per kg of body weight a week. EFSA said that many Europeans probably eat more than this. 34

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The atom

Al
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) outermost 3
Total13

Configuration [Ne] 3s² 3p¹

3s ↑ ↓
3p ↑
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 13 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Ne core, with one arrow per electron.

Related elements

Group 13
B Boron Ga Gallium In Indium Tl Thallium Nh Nihonium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Abridged Standard Atomic Weights 2024 .

    The atomic mass shown for the 84 elements that have a standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    European Commission, 2011. Commission Regulation (EU) No 1129/2011 establishing a Union list of food additives , Annex, Parts B and E.

    The text as adopted by the EU in 2011, from legislation.gov.uk. Later EU amendments are not in it.

    • E 173 Aluminium quantum satis only external coating of sugar confectionery for the decoration of cakes and pastries
  4. 4

    European Food Safety Authority (EFSA), The EFSA Journal (2008) 754, 2008. Safety of aluminium from dietary intake. Scientific Opinion of the Panel on Food Additives, Flavourings, Processing Aids and Food Contact Materials (AFC) , Summary.

    A copy of the EFSA opinion, hosted by the Czech food safety information centre. The EFSA Journal site (Wiley) was not used.

    • the Panel established a TWI of 1 mg aluminium/kg bw/week ... The TWI of 1 mg/kg bw/week is therefore likely to be exceeded in a significant part of the European population.
  5. 5

    National Institute of Standards and Technology (NIST), 2026. Atomic Weights and Isotopic Compositions for All Elements .

    Isotopic composition of each element; the most abundant isotope sets the neutron count in the nucleus view.