Name: Iridium 

Atomic Symbol and Mass Number: Ir [77]

Electron Configuration: [Xe] 4f   5d    6s

Atomic Radii: 136 pm

Electron Affinity: 151.0 kJ mol‑1

Oxidation States: -3, -1, 0,+1,+2,+3,+4,+5,+6,+7,+8,+9

Electronegativity Value: 2.20

Elemental Group: Transition Metal

Uses and Properties:

• Iridium is a hard, brittle, lustrous, dense, transition metal of the platinum family.

• It is silvery-white and it is notable for being the most corrosion resistant element known.

• It is unaffected by air, water and acids.

• It has a very high density and melting point. 

• Iridium is the most corrosion-resistant material known.

• It is used in special alloys and forms an alloy with osmium, which is used for pen tips and compass bearings. It was used in making the standard meter bar, which is an alloy of 90% platinum and 10% iridium.

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Lewis Diagram: