Element 77 · Iridium (Ir)

Iridium Bohr model: diagram and electrons per shell

The iridium Bohr model shows a iridium atom (Ir) as a small nucleus with its electrons circling it in 6 shells: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P. This page has a rotating 3D iridium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the iridium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of iridium (Ir), a simplified picture of a single iridium atom. Its nucleus holds 77 protons, and a neutral iridium atom has 77 electrons, arranged around it in 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P).

Ir K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 324s² 4p⁶ 4d¹⁰ 4f¹⁴ O · 155s² 5p⁶ 5d⁷ P · 26s²

Iridium Bohr model diagram

Bohr model diagram of iridium: a nucleus of 77 protons with 77 electrons on 6 shells, 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P, each ring labelled with its shell letter. — The iridium Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P).

Iridium electrons per shell

A neutral iridium atom has 77 electrons, one for each of its 77 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P.

Electrons in each shell of the iridium Bohr model
Shell	Shell number (n)	Electrons	Most it can hold (2n²)	Subshells
K	1	2	2	1s²
L	2	8	8	2s² 2p⁶
M	3	18	18	3s² 3p⁶ 3d¹⁰
N	4	32	32	4s² 4p⁶ 4d¹⁰ 4f¹⁴
O	5	15	50	5s² 5p⁶ 5d⁷
P	6	2	72	6s²

How the iridium Bohr model builds up, shell by shell

Watch the iridium Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P) as it forms.

Animation of the iridium Bohr model being built: a nucleus of 77 protons appears first, then each shell grows in around it and takes its electrons, giving 77 electrons on 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P). — The iridium Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P. Protons are red, neutrons yellow and electrons blue.

How to draw the iridium Bohr model

Find the atomic number. Iridium has atomic number 77, so a neutral atom has 77 protons and 77 electrons.
Draw the nucleus. Put a circle in the centre and write Ir in it. The 77 protons sit there with the neutrons.
Draw the shells. Sketch 6 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 15 in shell O and 2 in shell P.
Check the total. 2 + 8 + 18 + 32 + 15 + 2 = 77, the atomic number, so every electron is accounted for.

Atomic data for the iridium Bohr model

The numbers behind the iridium Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol: Ir
Atomic number: 77
Atomic mass: 192.2173 u
Family: Transition Metals
Position: group 9, period 6
Block: d-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁷
Shorthand: [Xe] 4f¹⁴ 5d⁷ 6s²
Electrons per shell: 2, 8, 18, 32, 15, 2
Outer-shell electrons: 2 in shell P

Ionisation energies

I₁: 880
I₂: 1600

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Calculated (pm): 180
Empirical (pm): 135
Covalent (pm): 122

Electronegativity and electron affinity

Electronegativity (Pauling): 2.2
Electron affinity (kJ/mol): 150.94

Oxidation states

+3 +4

Charges the element commonly takes in compounds.

Physical properties, abundance and history of iridium

Bulk properties of iridium, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions: Solid
Appearance: Silvery white
Melting point: 2445.85°C (2719 K)
Boiling point: 4129.85°C (4403 K)
Density: 22.56 g/cm³
Thermal conductivity (W/m·K): 147
Specific heat (J/g·K): 0.131
Molar heat capacity (J/mol·K): 25.1
Heat of fusion (kJ/mol): 27.61
Heat of vaporisation (kJ/mol): 604

Abundance

Earth's crust (mg/kg): 0.001

Discovery

Discovered by: Smithson Tennant
Year: 1803

Common compounds

Iridium Ir
Ammonium chloroiridate Cl6H8IrN2
Iridium-192 Ir
Hexachloroiridic acid Cl6H2Ir
Iridium tetrachloride Cl4Ir
Carbonylchlorobis(triphenylphosphine)iridium, trans- C37H30ClIrOP2-
Iridium trichloride Cl3Ir
Iridium(III) acetylacetonate C15H24IrO6

Compounds listed in the PubChem database.

Main isotopes of iridium

Isotopes of iridium share the same 77 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of iridium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
188	–	41.5 h	β⁺
189	–	13.2 d	EC
190	–	11.78 d	β⁺, e⁺
191	37.3 %	stable	–
192	–	73.82 d	β⁻, EC
193	62.7 %	stable	–

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about iridium

Iridium on the periodic table – properties, isotopes, uses and the full iridium page.
Transition Metals – all transition metal elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.