Element 45 · Transition metal
Rhodium (Rh) — Element 45
Greek rhodon — rose
Rhodium (Rh) is a transition metal in Period 5, Group 9 of the periodic table with atomic number 45, standard atomic weight 102.91 u, and ground-state electron configuration [Kr] 4d⁸ 5s¹. At standard temperature and pressure it is classified as a solid with 9 valence electrons and common oxidation states +3.
Catalytic converters, jewelry
What are the atomic properties and physical constants of Rhodium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 45
- Standard atomic mass
- 102.91 u
- Chemical family
- Transition metal
- Ground-state configuration
- [Kr] 4d⁸ 5s¹
- Electrons per shell
- 2, 8, 18, 16, 1
- Valence electrons
- 9
- Common ion charges / oxidation states
- +3
- Phase at STP
- Solid
- Pauling electronegativity
- 2.28 Pauling
- First ionization energy
- 720 kJ/mol
- Atomic radius
- 173 pm
- Melting point
- 1,964 °C
- Boiling point
- 3,695 °C
- Discovery year
- 1803
- Table coordinate
- Period 5, Group 9
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Rhodium’s shells?
A neutral Rhodium atom contains 45 electrons distributed across 5 occupied principal energy shells ([Kr] 4d⁸ 5s¹). The table below compares Rhodium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Rh | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 16 e⁻ | 32 e⁻ |
| n = 5 | O | 1 e⁻ | 50 e⁻ |
Frequently Asked Questions about Rhodium (Rh)
What is the atomic mass and atomic number of Rhodium (Rh)?
Rhodium (Rh) has atomic number Z = 45 (45 protons in its nucleus) and an IUPAC standard atomic weight of 102.91 u. It sits in Period 5, Group 9 and is classified as a transition metal.
What is the ground-state electron configuration of Rhodium?
The neutral ground-state electron configuration of Rhodium (Z = 45) is [Kr] 4d⁸ 5s¹. Across its 5 occupied principal shells (n = 1 to n = 5), the electrons per shell are 2, 8, 18, 16, 1, with 9 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Rhodium?
Rhodium commonly forms +3 oxidation states or ion charges in compounds. Its Pauling electronegativity is 2.28 and its first ionization energy is 720 kJ/mol.
When was Rhodium discovered and what is it used for?
Rhodium was discovered in 1803 (Greek rhodon — rose). Catalytic converters, jewelry
How does Rhodium compare to neighboring elements?
Other transition metal elements: