Atomic Number
21
Element 21
Scandium (Sc)
Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic d-block element, it has historically been classified as a rare-earth element.
Atomic Mass
44.956 u
Category
Transition Metal
Period
4
Group
Group 3: scandium group
Phase
solid
Density
2.99 g/cm3
Electron Shells
2, 8, 9, 2
Atomic Structure
Protons: 21. Electrons: 21. Neutrons: Varies by isotope.
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹
Why Scandium Matters
Scandium helps connect atomic number 21, transition metal behavior, period 4 trends, and electron shell structure. Its solid phase, atomic mass of 44.956 u, and electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹ make it useful for comparing bonding patterns across the periodic table.
Discovery and Occurrence
Scandium was discovered 1879 by Lars Fredrik Nilson. Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic d-block element, it has historically been classified as a rare-earth element.
Safety and Handling Context
Scandium is presented here for learning and comparison. Pure elements and laboratory compounds can have hazards that depend on dose, form, and setting.
Related Elements
Frequently Asked Questions
- What is the atomic number of Scandium?
- Scandium has atomic number 21, which means a neutral atom has 21 protons and 21 electrons.
- What is the chemical symbol for Scandium?
- The chemical symbol for Scandium is Sc.
- What category is Scandium in?
- Scandium is classified as a transition metal and sits in period 4 of the periodic table.
Explore Scandium in 3D
Use the interactive table above to rotate atomic models, compare periodic trends, and move from Scandium to neighboring elements without losing your place.