Chemical element · Atomic number 49
Indium
Indium in the periodic table: atomic number 49, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Post-transition metal
solid
114.818 u
Documented element sampleA block of pure indium weighing ten grams.
Image credit: François Nguyen
Auto-oriented, limited to 1600 × 1200 pixels and re-encoded as WebP; the subject was not altered.
Atomic classification
Shell occupancy
Indium in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 8 electrons
- M · n=3
- 18 electrons
- N · n=4
- 18 electrons
- O · n=5
- 3 electrons
- Electron configuration
- [Kr]5s2 4d10 5p1
- Electrons per shell
- 2 · 8 · 18 · 18 · 3
- Group
- 13
- Period
- 5
- Block
- P
- Element category
- Post-transition metal
Physical and chemical properties
- Atomic mass
- 114.818 u
- Standard state
- solid
- Density
- 7.31 g/cm³
- Melting point
- 429.75 K
- Boiling point
- 2,345 K
- Electronegativity
- 1.78 (Pauling)
- First ionisation energy
- 5.786 eV
- Oxidation states
- +3
- Discovery
- 1863
Safety and periodic classification
Safety
Safe handling cannot be inferred from Indium's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Indium is in period 5, group 13 and the P block. Its direct neighbours by atomic number are Cadmium and Tin. The recorded Pauling electronegativity is 1.78. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.
Where Indium sits among the 118 elements
The table compares the reported values for Indium with every other element that carries the same value in the snapshot. A rank is not a judgement, it is orientation: it says how unusual this value is across the periodic table.
| Value | Indium | Position in the data set |
|---|---|---|
| Melting point | 429.75 K | Rank 81 of 103 elements with a reported value. Highest: Carbon. |
| Boiling point | 2,345 K | Rank 51 of 93 elements with a reported value. Highest: Rhenium. |
| Density | 7.31 g/cm³ | Rank 43 of 96 elements with a reported value. Highest: Osmium. |
| Electronegativity (Pauling) | 1.78 | Rank 43 of 95 elements with a reported value. Highest: Fluorine. |
| Ionisation energy | 5.786 eV | Rank 84 of 102 elements with a reported value. Highest: Helium. |
All values and ranks come from the PubChem Periodic Table snapshot, retrieved on 2026-07-15. Elements without a reported value are excluded, so the population differs per row.
The neighbours of Indium in the periodic table
- Place in the table
- Group 13, period 5, P block. Classified as post-transition metal, solid at standard conditions.
- Direct neighbours
- Atomic number 49. Preceded by Cadmium, followed by Tin.
- Same group
- Same number of outer electrons, and therefore similar reactivity to Boron, Aluminum, Gallium, Thallium, Nihonium.
- Discovery
- Recorded in the snapshot as: 1863. Who, where and under what circumstances is not part of that record, so this page carries the sourced year and no discovery narrative.
- Oxidation states
- +3. They follow from the electron configuration [Kr]5s2 4d10 5p1 and indicate which compounds to expect.
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