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Periodic table / Transition metals

21Scandium

Scandium is a transition metal in group 3, period 4. At 25 °C it is a solid.

Sc
Shells: 2, 8, 9, 2. A simple picture: electrons do not move in circles.
Symbol
Sc
Atomic number
21 protons in the nucleus
Standard atomic weight
44.956 ± 0.001
Electron configuration
[Ar] 3d1 4s2
Electrons in each shell
2, 8, 9, 2
Group, period, block
3, 4, d
Family
Transition metals
State at 25 °C
solid
Electronegativity
1.36 (Pauling scale)
First ionisation energy
633.1 kJ/mol (6.56149 eV)
Where these numbers come from

Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.