Scandium Facts - Sc or Element 21

Scandium Chemical & Physical Properties

This is a photo of scandium. Scandium is a soft silvery metal.
This is a photo of scandium. Scandium is a soft silvery metal that develops a slight yellow or pink cast when exposed to air. Gibe, Free Documentation License

Scandium Basic Facts

Atomic Number: 21

Symbol: Sc

Atomic Weight: 44.95591

Discovery: Lars Nilson 1878 (Sweden)

Electron Configuration: [Ar] 4s2 3d1

Word Origin: Latin Scandia: Scandinavia

Isotopes: Scandium has 24 known isotopes ranging from Sc-38 to Sc-61. Sc-45 is the only stable isotope.

Properties: Scandium has a melting point of 1541 °C, boiling point of 2830 °C, specific gravity of 2.989 (25 °C), and valence of 3. It is a silvery-white metal which develops a yellowish or pinkish cast when exposed to air. Scandium is a very light, relatively soft metal. Scandium reacts rapidly with many acids. The blue color of aquamarine is attributed to the presence of scandium.

Sources: Scandium is found in the minerals thortveitite, euxenite and gadolinite. It is also produced as a byproduct of uranium refinement.

Uses: Scandium is used to make high intensity lamps. Scandium iodide is added to mercury vapor lamps to produce a light source with a color resembling sunlight. The radioactive isotope Sc-46 is used as a tracer in refinery crackers for crude oil.

Element Classification: Transition Metal

Scandium Physical Data

Density (g/cc): 2.99

Melting Point (K): 1814

Boiling Point (K): 3104

Appearance: somewhat soft, silvery-white metal

Atomic Radius (pm): 162

Atomic Volume (cc/mol): 15.0

Covalent Radius (pm): 144

Ionic Radius: 72.3 (+3e)

Specific Heat (@20°C J/g mol): 0.556

Fusion Heat (kJ/mol): 15.8

Evaporation Heat (kJ/mol): 332.7

Pauling Negativity Number: 1.36

First Ionizing Energy (kJ/mol): 630.8

Standard Reduction Potential: Sc3+ + e → Sc E0 = -2.077 V

Lattice Structure: Hexagonal

Lattice Constant (Å): 3.310

Lattice C/A Ratio: 1.594

CAS Registry Number: 7440-20-2

Scandium trivia:

  • Scandium was named after Scandinavia. Chemist Lars Nilson was attempting to isolate the element ytterbium from the minerals euxenite and gadolinite when he discovered scandium. These minerals were primarily found in the Scandinavia region.
  • Scandium is the transition metal with the lowest atomic number.
  • The discovery of scandium filled a spot predicted by Mendeleev's periodic table. Scandium took the place of the placeholder element eka-boron.
  • Most scandium compounds have scandium with the Sc3+ ion.
  • Scandium has an abundance in the Earth's crust of 22 mg/kg (or parts per million).
  • Scandium has an abundance in seawater of 6 x 10-7 mg/L (or parts per million).
  • Scandium is more abundant on the Moon than on Earth.

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.) International Atomic Energy Agency ENSDF database (Oct 2010)

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