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

Physical data from PubChem.¹

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. ²

The atom

Shell	Electrons
1 (K)	2
2 (L)	8
3 (M)	18
4 (N)	32
5 (O)	15
6 (P) outermost	2
Total	77

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

Sources

1

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

Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.
2
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.

Specimen

Can I eat it?

The atom

Related elements

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Sources