Rhodium (Rh)
[Kr] 4d⁸ 5s¹, an exception. 3 unpaired electrons, period 5, group 9, d block.
Element or ion
Type a symbol, a name or an atomic number, add a charge such as Fe3+ or Cl-, or tap an element in the table. Orbitals fill from m = −l up, spin +½ first.
RhRhodium, Z = 45, 102.906 u
[Kr] 4d8 5s1
In full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁸ 5s¹
- Blockd block
- Period5
- Group9
- Valence9
- Unpaired3
- MagneticPara
Last electron 4d
- n4shell
- l2d subshell
- m0orbital
- s−½spin down
Why Rh is an exception
Plain filling would give [Kr] 4d⁷ 5s². For heavier atoms the (n − 1)d, (n − 2)f and ns levels lie very close together, so one electron sits in d. These are the configurations found by experiment and printed in the NCERT tables.
Step by step
- Rhodium has 45 electrons.
- Fill in (n + l) order: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d⁷.
- That gives [Kr] 4d⁷ 5s², but the accepted configuration is [Kr] 4d⁸ 5s¹. For heavier atoms the (n − 1)d, (n − 2)f and ns levels lie very close together, so one electron sits in d. These are the configurations found by experiment and printed in the NCERT tables.
- Write the subshells in order of n: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁸ 5s¹.
- Replace the krypton core with [Kr]: [Kr] 4d⁸ 5s¹.
Rhodium (Rh): the numbers
| Atomic number | 45 |
|---|---|
| Atomic mass | 102.906 u |
| Period | 5 |
| Group | 9 |
| Block | d block |
| Valence electrons | 9 |
| Unpaired electrons | 3 |
| Magnetic | paramagnetic |
| Last electron | 4d: n = 4, l = 2, m = 0, s = −1/2 |
Rhodium (Rh): quick answers
What is the electronic configuration of rhodium?
Rhodium has 45 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁸ 5s¹, or [Kr] 4d⁸ 5s¹ in short.
Why is rhodium [Kr] 4d⁸ 5s¹ and not [Kr] 4d⁷ 5s²?
For heavier atoms the (n − 1)d, (n − 2)f and ns levels lie very close together, so one electron sits in d. These are the configurations found by experiment and printed in the NCERT tables.
What are the quantum numbers of the last electron of rhodium?
The last electron goes into 4d: n = 4, l = 2, m = 0, s = −1/2. Orbitals fill from m = −l up, spin +½ first.