Iridium (Ir): Bohr Model, Protons, Neutrons & Electrons
Iridium is element number 77, a transition metal in group 9, period 6. Its atom has 77 protons, 116 neutrons and 77 electrons arranged in 6 shells: 2, 8, 18, 32, 15, 2.
Protons, neutrons and electrons in iridium
The atomic number of iridium is 77, so every iridium atom has 77 protons. A neutral atom has the same number of electrons, 77. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For iridium-193, that is 193 − 77 = 116 neutrons. Iridium has 2 stable isotopes, with 114, 116 neutrons.
How to draw the Bohr model of iridium
- Draw the nucleus and write 77 p⁺ and 116 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 18 electrons on it.
- Draw the fourth shell and put 32 electrons on it.
- Draw the fifth shell and put 15 electrons on it.
- Draw the sixth shell and put 2 electrons on it.
- Check: 2 + 8 + 18 + 32 + 15 + 2 = 77 electrons, the same as the number of protons.
From potassium onwards the shells don’t simply fill as 2, 8, 8: the fourth shell starts before the third is full, so the real arrangement above (2, 8, 18, 32, 15, 2) is the one to draw.
Electron configuration
The electron configuration of iridium is [Xe] 6s² 4f¹⁴ 5d⁷. As a transition metal it fills an inner d-subshell, and its common ion is Ir³⁺.
Key facts about iridium
| Symbol | Ir |
|---|---|
| Atomic number | 77 |
| Relative atomic mass | 192.22 |
| Group · period · block | group 9 · period 6 · d-block |
| Type | Transition Metal |
| State at 25 °C | solid |
| Electron shells | 2, 8, 18, 32, 15, 2 |
| Electron configuration | [Xe] 6s² 4f¹⁴ 5d⁷ |
| Valence electrons | varies (outer shell: 2) |
| Common ion | Ir³⁺ |
| Electronegativity (Pauling) | 2.20 |
| First ionisation energy | 8.97 eV (865 kJ/mol) |
| Atomic radius (empirical) | 135 pm |
Where iridium sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does iridium have?
Iridium has 77 protons and 77 electrons (atomic number 77). Its most common isotope, iridium-193, has 193 − 77 = 116 neutrons.
What is the electron configuration of iridium?
[Xe] 6s² 4f¹⁴ 5d⁷. In shells that is 2, 8, 18, 32, 15, 2.
How many valence electrons does iridium have?
Iridium is a transition metal, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is iridium on the periodic table?
In group 9, period 6, in the d-block. It is a transition metal.
