Rhodium (Rh)
Element 45 · transition metal · group 9, period 5
Rhodium is element 45, a transition metal in group 9 and period 5. Its electron configuration is [Kr] 4d8 5s1. The shells fill 2, 8, 18, 16, 1. Courses differ here. Counting only the outer s subshell gives 1; counting the inner d subshell with it gives 9, which is the group number. It commonly forms ions with a charge of +3.
- 45 protons
- 1/9 valence e−
- +3
- d-block
Properties
| Atomic number | 45 |
|---|---|
| Symbol | Rh |
| Standard atomic weight | 102.91 u |
| Group | 9 |
| Period | 5 |
| Block | d-block |
| Category | transition metal |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1 |
| Noble-gas notation | [Kr] 4d8 5s1 |
| Electrons per shell | 2, 8, 18, 16, 1 |
| Valence electrons | 1 or 9 |
| Common ionic charge | +3 |
| Electronegativity (Pauling) | 2.28 |
| Protons / electrons | 45 / 45 |
Electron configuration of rhodium
Orbitals fill from the lowest energy upward. Writing that out for rhodium gives 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1, which is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1 in plain text.
Everything up to Kr is the same as in that noble gas, so it is usually abbreviated to [Kr] 4d8 5s1. The part outside the bracket is what does the chemistry.
| Subshell | Electrons | Capacity |
|---|---|---|
| 1s | 2 | 2 |
| 2s | 2 | 2 |
| 2p | 6 | 6 |
| 3s | 2 | 2 |
| 3p | 6 | 6 |
| 3d | 10 | 10 |
| 4s | 2 | 2 |
| 4p | 6 | 6 |
| 4d | 8 | 10 |
| 5s | 1 | 2 |
Rhodium ion charge
Rhodium commonly forms ions with a charge of +3.
Common questions
How many valence electrons does rhodium have?
There is no single agreed answer for rhodium. Courses differ here. Counting only the outer s subshell gives 1; counting the inner d subshell with it gives 9, which is the group number. Check which convention your course uses before answering.
What is the electron configuration of rhodium?
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1, or [Kr] 4d8 5s1 written from the previous noble gas. Orbitals fill lowest energy first, but rhodium is one of the elements that breaks that order - a half-filled or filled d subshell is stable enough to be worth borrowing an s electron for.
What is the charge of rhodium?
Rhodium commonly forms ions with a charge of +3. Transition metals have several accessible oxidation states, which is why more than one charge is listed.
How many protons, electrons and neutrons does rhodium have?
A neutral rhodium atom has 45 protons and 45 electrons. Its standard atomic weight is 102.91, so the most common isotope has about 58 neutrons.
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