Element 21 · Transition metal
Scandium (Sc) — Element 21
Latin Scandia — Scandinavia
Scandium (Sc) is a transition metal in Period 4, Group 3 of the periodic table with atomic number 21, standard atomic weight 44.956 u, and ground-state electron configuration [Ar] 3d¹ 4s². At standard temperature and pressure it is classified as a solid with 3 valence electrons and common oxidation states +3.
Aerospace alloys, stadium lights
What are the atomic properties and physical constants of Scandium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 21
- Standard atomic mass
- 44.956 u
- Chemical family
- Transition metal
- Ground-state configuration
- [Ar] 3d¹ 4s²
- Electrons per shell
- 2, 8, 9, 2
- Valence electrons
- 3
- Common ion charges / oxidation states
- +3
- Phase at STP
- Solid
- Pauling electronegativity
- 1.36 Pauling
- First ionization energy
- 633 kJ/mol
- Atomic radius
- 184 pm
- Melting point
- 1,541 °C
- Boiling point
- 2,836 °C
- Discovery year
- 1879
- Table coordinate
- Period 4, Group 3
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Scandium’s shells?
A neutral Scandium atom contains 21 electrons distributed across 4 occupied principal energy shells ([Ar] 3d¹ 4s²). The table below compares Scandium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Sc | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 9 e⁻ | 18 e⁻ |
| n = 4 | N | 2 e⁻ | 32 e⁻ |
Frequently Asked Questions about Scandium (Sc)
What is the atomic mass and atomic number of Scandium (Sc)?
Scandium (Sc) has atomic number Z = 21 (21 protons in its nucleus) and an IUPAC standard atomic weight of 44.956 u. It sits in Period 4, Group 3 and is classified as a transition metal.
What is the ground-state electron configuration of Scandium?
The neutral ground-state electron configuration of Scandium (Z = 21) is [Ar] 3d¹ 4s². Across its 4 occupied principal shells (n = 1 to n = 4), the electrons per shell are 2, 8, 9, 2, with 3 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Scandium?
Scandium commonly forms +3 oxidation states or ion charges in compounds. Its Pauling electronegativity is 1.36 and its first ionization energy is 633 kJ/mol.
When was Scandium discovered and what is it used for?
Scandium was discovered in 1879 (Latin Scandia — Scandinavia). Aerospace alloys, stadium lights
How does Scandium compare to neighboring elements?
Other transition metal elements: