Zirconium (Zr)
Zirconium is element 40, a transition metal in group 4, period 5. A neutral atom has 40 protons, 51 neutrons and 40 electrons, 2 of them valence electrons.
Transition metal- Atomic number
- 40
- Atomic mass
- 91.22 u
- Valence electrons
- 2*
- Protons · neutrons
- 40 · 51
- Electrons per shell
- 2, 8, 18, 10, 2
- At room temperature
- solid
Bohr model of zirconium
The Bohr model draws zirconium as a nucleus of 40 protons and 51 neutrons, with its 40 electrons on 5 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 10 in shell 4, 2 in shell 5. Press Build the atom to watch the shells fill from the inside out. The outer ring (the O shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of zirconium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d²
Short form (noble gas notation): [Kr] 5s² 4d². The [Kr] stands for the electrons of krypton, the noble gas before it.
How many valence electrons does zirconium have?
Zirconium has 2 valence electrons.
Zirconium is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 5), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 40 | equal to the atomic number |
|---|---|---|
| Electrons | 40 | equal to the protons in a neutral atom |
| Neutrons | 51 | mass number 91 − 40 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Zirconium properties
| Symbol | Zr |
|---|---|
| Category | Transition metal |
| Group · period · block | 4 · 5 · d |
| Atomic mass | 91.22 u |
| State at 25 °C | solid |
| Melting point | 2,128 K (1,850 °C, 3,370 °F) |
| Boiling point | 4,682 K (4,410 °C, 7,970 °F) |
| Density | 6.52 g/cm³ |
| Electronegativity (Pauling) | 1.33 |
| Atomic radius | 186 pm |
| First ionization energy | 6.634 eV |
| Electron affinity | 0.426 eV |
| Oxidation states | +4 |
| Common ion charge | +4 |
| Discovered | 1789 by Martin Heinrich Klaproth |
Where zirconium sits on the periodic table
Group 4: Titanium, Hafnium, Rutherfordium.
Questions about zirconium
How many valence electrons does zirconium have?
Zirconium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does zirconium have?
A neutral zirconium atom has 40 protons and 40 electrons. Its most common form has about 51 neutrons (mass number 91 − 40 protons).
What is the electron configuration of zirconium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d², written in short form as [Kr] 5s² 4d².
What does the Bohr model of zirconium look like?
A nucleus of 40 protons and 51 neutrons, circled by 5 electron shells holding 2, 8, 18, 10, 2 electrons.
What is the atomic number of zirconium?
40. The atomic number is the number of protons in the nucleus, and it is what makes an atom zirconium.