Scandium (Sc)
Element 21 · Transition metal · atomic mass 44.956 u · group 3, period 4
Electron shells: 2, 8, 9, 2
Scandium is a light, strong transition metal that Mendeleev predicted before anyone found it. It is not especially rare, just annoyingly diffuse — it rarely concentrates into an ore.
Mendeleev predicted it as "eka-boron" in 1869, a decade before it was isolated.
- Atomic number
- 21
- Atomic mass
- 44.956 u
- Electron configuration
- [Ar] 4s² 3d¹
- Group · period · block
- 3 · 4 · d
- Oxidation states
- +3
- Electronegativity
- 1.36 (Pauling)
- Melting point
- 1,541 °C
- Boiling point
- 2,836 °C
- Density
- 2.99 g/cm³
- State at 20 °C
- Solid
- Appearance
- Silvery-white metal
- Discovered
- Lars Fredrik Nilson, 1879
21 protons, and 21 electrons when neutral
IUPAC standard atomic weight
Group 3
What Scandium is used for
- Aluminium-scandium alloys for aerospace and bikes
- Metal-halide stadium lighting
- Solid oxide fuel cells
- Research tracers
Atomic structure of Scandium
A neutral scandium atom has 21 protons and 21 electrons. Its most common isotope carries about 24 neutrons, which is where the mass number 45 comes from. Change the neutron count and you have a different isotope of scandium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 9, 2. In orbital notation that is [Ar] 4s² 3d¹. As a d-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Scandium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Scandium sits in the periodic table
Discovery and naming
Scandium was discovered by Lars Fredrik Nilson in 1879. Its name comes from Latin Scandia, "Scandinavia".
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Scandium?
The standard atomic weight of Scandium is 44.956 u, as published by IUPAC's Commission on Isotopic Abundances and Atomic Weights.
How many protons, neutrons and electrons does Scandium have?
Scandium has 21 protons, because the atomic number is the proton count and that is what makes an atom Scandium at all. A neutral Scandium atom has the same number of electrons, 21. The neutron count varies by isotope; the most common one has about 24, since 45 − 21 = 24.
What is the electron configuration of Scandium?
The electron configuration of Scandium is [Ar] 4s² 3d¹. Its electrons are arranged 2, 8, 9, 2 across 4 shells.
Is Scandium a metal?
Yes. Scandium is classified as a transition metal, on the metallic side of the table.
What group and period is Scandium in?
Scandium is in group 3 (the group 3), period 4, in the d-block. The group is its column and the period is its row.
What is the charge of Scandium?
Scandium most commonly forms a 3+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound.
What is the melting point of Scandium?
Scandium melts at 1,541 °C and boils at 2,836 °C. That puts it in the solids at everyday temperatures.
What is Scandium used for?
Aluminium-scandium alloys for aerospace and bikes, Metal-halide stadium lighting, Solid oxide fuel cells, Research tracers. Scandium is a light, strong transition metal that Mendeleev predicted before anyone found it.
Who discovered Scandium, and where does its name come from?
Scandium (Sc) was discovered by Lars Fredrik Nilson in 1879. The name comes from Latin Scandia, "Scandinavia".