Atomic Number
77
Element 77
Iridium (Ir)
Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the second-densest element (after osmium).
Atomic Mass
192.22 u
Category
Transition Metal
Period
6
Group
Group 9: cobalt group
Phase
solid
Density
22.56 g/cm3
Electron Shells
2, 8, 18, 32, 15, 2
Atomic Structure
Protons: 77. Electrons: 77. Neutrons: Varies by isotope.
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁷
Why Iridium Matters
Iridium helps connect atomic number 77, transition metal behavior, period 6 trends, and electron shell structure. Its solid phase, atomic mass of 192.22 u, and electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d⁷ make it useful for comparing bonding patterns across the periodic table.
Discovery and Occurrence
Iridium was discovered 1803 by Smithson Tennant. Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the second-densest element (after osmium).
Safety and Handling Context
Iridium is presented here for learning and comparison. Pure elements and laboratory compounds can have hazards that depend on dose, form, and setting.
Related Elements
Frequently Asked Questions
- What is the atomic number of Iridium?
- Iridium has atomic number 77, which means a neutral atom has 77 protons and 77 electrons.
- What is the chemical symbol for Iridium?
- The chemical symbol for Iridium is Ir.
- What category is Iridium in?
- Iridium is classified as a transition metal and sits in period 6 of the periodic table.
Explore Iridium in 3D
Use the interactive table above to rotate atomic models, compare periodic trends, and move from Iridium to neighboring elements without losing your place.