Chemical element · Atomic number 40
Zirconium
Zirconium in the periodic table: atomic number 40, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Transition metal
solid
91.22 u
Documented element sampleA documented sample of elemental zirconium, a silvery-gray metal.
Image credit: James St. John
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Zirconium in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 10 electrons
- O · n=5
- 2 electrons
- Electron configuration
- [Kr]5s2 4d2
- Electrons per shell
- 2 · 8 · 18 · 10 · 2
- Group
- 4
- Period
- 5
- Block
- D
- Element category
- Transition metal
Physical and chemical properties
- Atomic mass
- 91.22 u
- Standard state
- solid
- Density
- 6.52 g/cm³
- Melting point
- 2,128 K
- Boiling point
- 4,682 K
- Electronegativity
- 1.33 (Pauling)
- First ionisation energy
- 6.634 eV
- Oxidation states
- +4
- Discovery
- 1789
Safety and periodic classification
Safety
Safe handling cannot be inferred from Zirconium's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Zirconium is in period 5, group 4 and the D block. Its direct neighbours by atomic number are Yttrium and Niobium. The recorded Pauling electronegativity is 1.33. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Zirconium sits among the 118 elements
The table compares the reported values for Zirconium with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Zirconium | Position in the data set |
|---|---|---|
| Melting point | 2,128 K | Rank 16 of 103 elements with a reported value. Highest: Carbon. |
| Boiling point | 4,682 K | Rank 10 of 93 elements with a reported value. Highest: Rhenium. |
| Density | 6.52 g/cm³ | Rank 55 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 1.33 | Rank 59 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 6.634 eV | Rank 58 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Zirconium in the periodic table
- Place in the table
- Group 4, period 5, D block. Classified as transition metal, solid at standard conditions.
- Direct neighbours
- Atomic number 40. Preceded by Yttrium, followed by Niobium.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Titanium, Hafnium, Rutherfordium.
- Discovery
- Recorded in the snapshot as: 1789. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- +4. They follow from the electron configuration [Kr]5s2 4d2 and indicate which compounds to expect.
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