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Indium

Element 49 · Post-transition metal

Specimen

Atomic number
49
Atomic mass
114.82
State at room temperature
Solid
Melting point
156.6 °C
Boiling point
2,072 °C
Density
7.31 g/cm³
Discovered
1863

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

Can I eat it?

In food and water
Not needed, little harm known. Indium has no known function in the body. In rat studies, the gut absorbed little indium phosphide. The RSC says more than a few milligrams is toxic. There are few studies of indium taken by mouth. 34

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The atom

In
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 18
5 (O) outermost 3
Total49

Configuration [Kr] 4d¹⁰ 5s² 5p¹

4d ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓
5s ↑ ↓
5p ↑
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 49 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 Kr core, with one arrow per electron.

Related elements

Group 13
B Boron Al Aluminium Ga Gallium Tl Thallium Nh Nihonium

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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

    U.S. National Toxicology Program, 2001. Toxicology and Carcinogenesis Studies of Indium Phosphide in F344/N Rats and B6C3F1 Mice (Inhalation Studies), TR-499 .

    • Indium phosphide was poorly absorbed from the gastrointestinal tract in both oral studies, with most of the indium being excreted in the feces.
  4. 4

    Royal Society of Chemistry, 2026. Indium - Element information, properties and uses .

    • Indium has no known biological role. It is toxic if more than a few milligrams are consumed
  5. 5

    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.