Rhodium (Rh): electron configuration, atomic mass and facts
Rhodium (Rh) is element 45 of the periodic table, a transition metal in period 5, group 9. Its electron configuration is [Kr] 4d8 5s1, with electrons arranged in shells 2, 8, 18, 16, 1, and its standard atomic weight is 102.91 u.
▶ Watch Rhodium’s electrons orbit in the interactive periodic tableRhodium at a glance
| Symbol | Rh |
|---|---|
| Atomic number | 45 |
| Atomic mass | 102.91 u |
| Category | Transition metal |
| Group | 9 |
| Period | 5 |
| Block | d-block |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1 |
| Noble-gas shorthand | [Kr] 4d8 5s1 |
| Electrons per shell | 2, 8, 18, 16, 1 |
| Electronegativity (Pauling) | 2.28 |
| State at 20 °C | solid |
Where is Rhodium on the periodic table?
Rhodium is in period 5, group 9, in the d-block. The period number matches its 5 electron shells, and the block names the subshell its last electrons fill. In the same group, Cobalt sits directly above it and Iridium sits directly below it. Elements in the same column of the d-block often have similar chemistry.
How to work out the electron configuration of Rhodium
Put 45 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), 4d⁷ (45). Rhodium is one of the exceptions to this filling order: experiments show its ground state is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁸ rather than 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁷, because the neighbouring subshells are so close in energy. In shorthand, [Kr] stands for the 36 electrons of krypton, giving [Kr] 4d⁸ 5s¹.
How electronegative is Rhodium?
Rhodium has a Pauling electronegativity of 2.28, ranking 15 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 Rhodium?
The electron configuration of Rhodium (Rh) is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1. In noble-gas shorthand it is written [Kr] 4d8 5s1.
How many electrons does Rhodium have in each shell?
Rhodium has 45 electrons arranged in shells as 2, 8, 18, 16, 1.
What is the atomic mass of Rhodium?
The standard atomic weight of Rhodium is 102.91 u, so one mole of Rhodium atoms has a mass of about 102.91 g.
Is Rhodium a metal?
Yes. Rhodium is a transition metal.
Explore nearby elements
More transition metals: Molybdenum, Technetium, Ruthenium, Palladium, Silver, Cadmium. See all elements on the periodic table.