An Overview of 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, a boiling point of 2830 °C, a 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

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
• Oxidation States: 3
• 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

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)