Element 40 · Transition metal
Zirconium (Zr) — Element 40
Persian zargun — gold-like
Zirconium (Zr) is a transition metal in Period 5, Group 4 of the periodic table with atomic number 40, standard atomic weight 91.224 u, and ground-state electron configuration [Kr] 4d² 5s². At standard temperature and pressure it is classified as a solid with 4 valence electrons and common oxidation states +4.
Nuclear cladding, ceramics
What are the atomic properties and physical constants of Zirconium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 40
- Standard atomic mass
- 91.224 u
- Chemical family
- Transition metal
- Ground-state configuration
- [Kr] 4d² 5s²
- Electrons per shell
- 2, 8, 18, 10, 2
- Valence electrons
- 4
- Common ion charges / oxidation states
- +4
- Phase at STP
- Solid
- Pauling electronegativity
- 1.33 Pauling
- First ionization energy
- 640 kJ/mol
- Atomic radius
- 206 pm
- Melting point
- 1,855 °C
- Boiling point
- 4,409 °C
- Discovery year
- 1789
- Table coordinate
- Period 5, Group 4
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Zirconium’s shells?
A neutral Zirconium atom contains 40 electrons distributed across 5 occupied principal energy shells ([Kr] 4d² 5s²). The table below compares Zirconium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Zr | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 10 e⁻ | 32 e⁻ |
| n = 5 | O | 2 e⁻ | 50 e⁻ |
Frequently Asked Questions about Zirconium (Zr)
What is the atomic mass and atomic number of Zirconium (Zr)?
Zirconium (Zr) has atomic number Z = 40 (40 protons in its nucleus) and an IUPAC standard atomic weight of 91.224 u. It sits in Period 5, Group 4 and is classified as a transition metal.
What is the ground-state electron configuration of Zirconium?
The neutral ground-state electron configuration of Zirconium (Z = 40) is [Kr] 4d² 5s². Across its 5 occupied principal shells (n = 1 to n = 5), the electrons per shell are 2, 8, 18, 10, 2, with 4 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Zirconium?
Zirconium commonly forms +4 oxidation states or ion charges in compounds. Its Pauling electronegativity is 1.33 and its first ionization energy is 640 kJ/mol.
When was Zirconium discovered and what is it used for?
Zirconium was discovered in 1789 (Persian zargun — gold-like). Nuclear cladding, ceramics
How does Zirconium compare to neighboring elements?
Other transition metal elements: