Rhodium (Rh)
Rhodium is element 45, a transition metal in period 5, group 9 of the periodic table. At room temperature it is a solid.
Electron configuration [Kr] 4d8 5s1
Electrons per shell 2, 8, 18, 16, 1
Rhodium data
| Atomic number | 45 |
|---|---|
| Symbol | Rh |
| Atomic mass | 102.906 u |
| Category | Transition metal |
| Group | 9 |
| Period | 5 |
| Block | d |
| State at 25 °C | solid |
| Melting point | 2237 K (1963.9 °C) |
| Boiling point | 3968 K (3694.9 °C) |
| Density | 12.45 g/cm³ |
| Electronegativity (Pauling) | 2.28 |
| Atomic radius | 135 pm |
| 1st ionization energy | 720 kJ/mol |
| Electron affinity | -110 kJ/mol |
| Oxidation states | -1, +1, +2, +3, +4, +5, +6 |
| Common ion charge | 3+ |
| Discovered | 1803 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through rhodium’s configuration and its ions →
Where rhodium sits
Rhodium belongs to the transition metals. Its Pauling electronegativity of 2.28 is mid-range; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Rhodium FAQ
What is the electron configuration of rhodium?
Rhodium (Z = 45) has the configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1. In noble-gas shorthand that is [Kr] 4d8 5s1. This is an exception to the simple Aufbau prediction (1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d7 5s2); a half-filled or filled subshell lowers the energy.
How many valence electrons does rhodium have?
9 (1 outer s + 8 d electrons; 1 in the outermost shell).
What is the atomic mass of rhodium?
The standard atomic weight of rhodium is 102.906 u, so one mole weighs 102.906 g.
Is rhodium a metal?
Yes. Rhodium is a transition metal.
What is the charge of a rhodium ion?
Rhodium most commonly forms Rh3+.