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Iridium

Element 77 · Transition metal

Specimen

Atomic number
77
Atomic mass
192.22
State at room temperature
Solid
Melting point
2,446 °C
Boiling point
4,428 °C
Density
22.42 g/cm³
Discovered
1803

Atomic mass from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Not needed, little harm known. Iridium is one of the rarest elements on Earth. The body does not use it. The RSC says it has low toxicity, but there are few studies of it. 3

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The atom

Ir
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 32
5 (O) 15
6 (P) outermost 2
Total77

Configuration [Xe] 4f¹⁴ 5d⁷ 6s²

4f ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
5d ↑ ↓ ↑ ↓ ↑ ↑ ↑
6s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 77 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Xe core, with one arrow per electron.

Related elements

Group 9
Co Cobalt Rh Rhodium Mt Meitnerium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Abridged Standard Atomic Weights 2024 .

    The atomic mass shown for the 84 elements that have a standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    Royal Society of Chemistry, Periodic Table, 2026. Iridium - Element information, properties and uses .

    Reference page; its Biological role and Natural abundance sections are quoted.

    • Iridium has no known biological role, and has low toxicity. Natural abundance Iridium is one of the rarest elements on Earth.
  4. 4

    National Institute of Standards and Technology (NIST), 2026. Atomic Weights and Isotopic Compositions for All Elements .

    Isotopic composition of each element; the most abundant isotope sets the neutron count in the nucleus view.