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Scandium

Element 21 · Transition metal

Specimen

Atomic number
21
Atomic mass
44.956
State at room temperature
Solid
Melting point
1,541 °C
Boiling point
2,836 °C
Density
2.99 g/cm³
Discovered
1879

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

Can I eat it?

In food and water
Not needed, little harm known. Little is known about what scandium does in the body. Researchers consider it of low toxicity. Under US law, scandium chloride is classed as moderately toxic when swallowed. 3

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The atom

Sc
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 9
4 (N) outermost 2
Total21

Configuration [Ar] 3d¹ 4s²

3d ↑
4s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 21 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 Ar core, with one arrow per electron.

Related elements

Group 3
Y Yttrium Lu Lutetium Lr Lawrencium

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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

    Sánchez-González C. et al., The Scientific World Journal 2013:782745, 2013. Accumulation of Scandium in Plasma in Patients with Chronic Renal Failure , Introduction.

    • information about its physiological and/or toxicological role is very limited. Although Sc is considered to present low toxicity, under the US Toxic Substances Control Act, scandium chloride is classed as a poison by the intraperitoneal route and as moderately toxic by ingestion
  4. 4

    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.