Scandium (Sc)

Stable Isotopes of Scandium

Isotope Z(p) N(n) Atomic Mass Natural Abundance Nuclear Spin
Sc-45 21 24 44.955910 100.00% 7/2-


Scandium was discovered in 1879 by Lars Fredrik Nilson in the minerals euxenite and gadolinite, which had not yet been found anywhere except in Scandinavia. Its name originates from the Latin word Scandia, which means “Scandinavia.”

Scandium is a silvery white solid that is soft and light and turns slightly yellow when exposed to air. It is chemically similar to the rare earths. It does not tarnish in air, and it decomposes in water. It exhibits two allotropic modifications: a hexagonal close-packed structure that is stable up to 1335 ºC transforms into a body-centered cubic form above 1335 ºC. Scandium is strongly electropositive. It reacts with oxygen, forming its only oxide, Sc2O3. The reaction is slow on bulk metal at ordinary temperatures but rapid above 500 ºC. The metal reacts with water, liberating hydrogen. Scandium metal reacts rapidly with most acids, liberating hydrogen and forming salts upon evaporation of the solution.

The metal is used to produce high-intensity lights. Its iodide is added to mercury vapor lamps to form very bright indoor lights. Radioactive Scandium-46 is used as a tracer for crude oil.

Properties of Scandium

Name Scandium
Symbol Sc
Atomic number 21
Atomic weight 44.956
Standard state Solid at 298 °K
CAS Registry ID 7440-20-2
Group in periodic table 3
Group name None
Period in periodic table 4
Block in periodic table d-block
Color Silvery white
Classification Metallic
Melting point 1541 °C
Boiling point 2831 °C
Thermal conductivity 15.8 W/(m·K) at 298.2 °K
Electrical resistivity 61.0 µΩ·cm at 22 °C
Electronegativity 1.30
Specific heat 0.57 kJ/kg K
Heat of vaporization 318 kJ·mol-1
Heat of fusion 16 kJ·mol-1
Density of solid 2.99 g/cm3
Electron configuration [Ar]3d14s2
Atomic radius 1.62 Å
Ionic radius Sc3+: 0.75 Å (coordination number 6)
Oxidation state +3

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