Indium (In)
Post-transition metal · p-block · period 5 · group 13
Very soft, silvery metal that leaves a mark on paper like a pencil.
Indium (symbol In) is chemical element number 49, a post-transition metal in group 13, period 5 of the periodic table. Its standard atomic weight is 114.82 and its electron configuration is [Kr] 4d10 5s2 5p1. At room temperature it is a solid. Named after the bright indigo line it shows in a spectroscope.
Properties
| Atomic number | 49 |
|---|---|
| Atomic mass | 114.82 |
| Category | Post-transition metal |
| Block | p-block |
| Group · Period | 13 · 5 |
| Electron configuration | [Kr] 4d10 5s2 5p1 |
| Electrons per shell | 2, 8, 18, 18, 3 |
| State at 25 °C | solid |
| Melting point | 429.75 K |
| Boiling point | 2345 K |
| Density | 7.31 g/cm³ |
| Electronegativity (Pauling) | 1.78 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1863 · Reich & Richter |
Key facts about Indium
- Named after the bright indigo line it shows in a spectroscope.
- So soft it can be dented with a fingernail, and it 'screams' (crackles) when bent.
- Indium tin oxide is the transparent conductor coated on nearly every touchscreen.
- Stays workable and non-brittle even at extremely low temperatures.
What Indium is used for
Transparent electrodes for touchscreens and LCDs, low-melting solders and seals, semiconductors, mirrors.
Where it sits in the periodic table
Indium is in group 13, period 5, of the p-block. Its electron configuration [Kr] 4d10 5s2 5p1 means its outermost shell holds 3 electrons, which is what places it here and explains much of its chemistry. See Indium on the interactive table →
Indium — frequently asked questions
What is Indium used for?
Transparent electrodes for touchscreens and LCDs, low-melting solders and seals, semiconductors, mirrors.
Is Indium radioactive?
No. Indium has at least one stable isotope and is not radioactive.
What is the electron configuration of Indium?
Indium has the electron configuration [Kr] 4d10 5s2 5p1, which is 2, 8, 18, 18, 3 electrons per shell.
What group and period is Indium in?
Indium is in group 13, period 5, in the p-block. Its outer shell holds 3 electrons.
Who discovered Indium?
Indium was discovered in 1863 by Reich & Richter.