Indium (In): electron configuration, atomic mass and facts
Indium (In) is element 49 of the periodic table, a post-transition metal in period 5, group 13. Its electron configuration is [Kr] 4d10 5s2 5p1, with electrons arranged in shells 2, 8, 18, 18, 3, and its standard atomic weight is 114.82 u.
▶ Watch Indium’s electrons orbit in the interactive periodic tableIndium at a glance
| Symbol | In |
|---|---|
| Atomic number | 49 |
| Atomic mass | 114.82 u |
| Category | Post-transition metal |
| Group | 13 |
| Period | 5 |
| Block | p-block |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p1 |
| Noble-gas shorthand | [Kr] 4d10 5s2 5p1 |
| Electrons per shell | 2, 8, 18, 18, 3 |
| Outer-shell electrons | 3 |
| Electronegativity (Pauling) | 1.78 |
| State at 20 °C | solid |
Where is Indium on the periodic table?
Indium is in period 5, group 13, in the p-block. The period number matches its 5 electron shells, and the block names the subshell its last electrons fill. In the same group, Gallium sits directly above it and Thallium sits directly below it. Elements in one group have the same number of outer-shell electrons (3 here), which is why they react in similar ways.
How to work out the electron configuration of Indium
Put 49 electrons into subshells in order of rising energy, filling each before starting the next: 1s² (2), 2s² (4), 2p⁶ (10), 3s² (12), 3p⁶ (18), 4s² (20), 3d¹⁰ (30), 4p⁶ (36), 5s² (38), 4d¹⁰ (48), 5p¹ (49). In shorthand, [Kr] stands for the 36 electrons of krypton, giving [Kr] 4d¹⁰ 5s² 5p¹.
How electronegative is Indium?
Indium has a Pauling electronegativity of 1.78, ranking 44 of the 100 elements with a known value (fluorine is highest at 3.98). That is in the middle of the range.
Frequently asked questions
What is the electron configuration of Indium?
The electron configuration of Indium (In) is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p1. In noble-gas shorthand it is written [Kr] 4d10 5s2 5p1.
How many electrons does Indium have in each shell?
Indium has 49 electrons arranged in shells as 2, 8, 18, 18, 3. It has 3 electrons in its outer shell.
What is the atomic mass of Indium?
The standard atomic weight of Indium is 114.82 u, so one mole of Indium atoms has a mass of about 114.82 g.
Is Indium a metal?
Yes. Indium is a post-transition metal.
Explore nearby elements
More post-transition metals: Gallium, Tin, Thallium, Lead, Bismuth, Polonium. See all elements on the periodic table.