Atomic / phase data
Reference values are evaluated.
FCC structure
Pure rhodium metal is FCC.
Catalysis
Catalytic chemistry is experimentally established; application wording is reviewed.
Market price
Price is intentionally excluded as a fixed intrinsic property because it is volatile.
Geography
PGM supply/recycling context is broad and dated.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Rhodium (Rh)
Rhodium is element 45, a rare platinum-group transition metal. Its FCC lattice and surface chemistry underpin catalytic-converter and industrial-catalysis roles, while rhodium plating is a distinct thin-coating application—not the definition of the element.
Rhodium atomic number, mass, electron configuration and key properties
Rhodium: quick answers
How many protons, neutrons and electrons does rhodium have?
Rhodium’s atomic number is 45, so every rhodium atom has 45 protons, and a neutral atom also has 45 electrons. Its most common natural isotope, rhodium-103, has 58 neutrons (other isotopes have different neutron counts).
What is the symbol for rhodium?
The chemical symbol for rhodium is Rh.
Is rhodium a solid, liquid or gas at room temperature?
Rhodium is a solid at room temperature (about 25 °C).
What family (group) is rhodium in?
Rhodium is a transition metal, in group 9, period 5 of the periodic table.
What is the electron configuration of rhodium?
The ground-state electron configuration of rhodium is [Kr] 4d⁸ 5s¹.
From atomic number to chemistry
Read these as a chain of causes, not as isolated facts. Each step links to the concept hub if you want the underlying idea explained.
45 protons define rhodium.
The reference ground-state configuration frames atomic and chemical behavior.
Periodic position organizes recurring trends without replacing element-specific evidence.
The teaching nucleus is one isotope, not the relative atomic mass.
Phase claims preserve measured/evaluated/predicted/unknown evidence labels.
Rhodium in its period and family
Rhodium lies in Period 5, Group 9 between ruthenium and palladium. Its d-electron chemistry supports several oxidation states and powerful catalytic surface/complex behavior.
Rhodium Visual Lab
Explore Rh across the teaching nucleus, isolated-atom orbitals, evidence-aware material structure and temperature/evidence views, then connect those models to uses, isotopes and source-backed context.
Every mark points to one exact feature
The numbered markers explain the same information system used throughout Element Lookup. Unknown or predicted fields remain visibly labelled rather than being replaced with guesses.
Rhodium in one minute
Atomic number 45 means 45 protons.
Rh is the symbol for rhodium.
Rhodium is a platinum-group transition metal.
Pure rhodium is FCC and extremely corrosion resistant.
Rhodium plating and rhodium catalysts are applications of the element, not separate elements.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 16 · 1 electrons
Representative 4d and 5s isolated-atom clouds do not show metallic bands or ligand-field orbitals in rhodium catalysts.
Pure rhodium is face-centred cubic near room temperature. The viewer shows a conventional FCC teaching cell.. The viewer is evidence-aware: measured structures are identified as such; unknown bulk structures stay unknown.
Teaching visualization; not a literal finite sample or thermal trajectory.What this model does—and does not—show
Representative 4d and 5s isolated-atom clouds do not show metallic bands or ligand-field orbitals in rhodium catalysts.
Where do I meet rhodium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Emission-control catalysts
Rhodium is especially important in catalytic converters for reactions that reduce nitrogen oxides.
FCC noble PGM → catalytic surface → recycling loop
Rhodium is best understood as a surface-chemistry and circular-supply story rather than a jewelry-price story.
FCC rhodium
Pure rhodium is a dense, corrosion-resistant FCC metal.
Cobalt, rhodium and iridium
Group 9 spans a common 3d metal and two platinum-group metals with increasingly heavy-atom chemistry.
| Period | 4 |
|---|---|
| Context | HCP/FCC allotropy |
| Period | 5 |
|---|---|
| Crystal | FCC |
| Period | 6 |
|---|---|
| Context | dense PGM |
Rhodium properties: atomic, physical, thermal and chemical
Categories follow the science of this element rather than a fixed decorative template. Each row carries condition/provenance context and an evidence label; unknown values stay unknown.
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Atomic number | 45 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | 102.906 | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Kr] 4d⁸ 5s¹ | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group 9 · Period 5 · d-block | Periodic-table placement | Evaluated |
| Electronegativity | 2.28 | Source-reviewed; see Sources below | Evaluated |
| Reference isotope | ¹⁰³Rh | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Hard silvery-white noble metal | Source-reviewed; see Sources below | Evaluated |
| Density | 12.4 g/cm³ | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Face-centred cubic | Pure rhodium is face-centred cubic near room temperature. The viewer shows a conventional FCC teaching cell. | Measured |
| Classification | Transition metal · platinum-group metal | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | Pure rhodium is face-centred cubic near room temperature. The viewer shows a conventional FCC teaching cell. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 2236 K | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | 3968 K | Source-reviewed; see Sources below | Evaluated |
| Phase-path context | At approximately standard pressure, rhodium is solid below 2236 K, liquid to about 3968 K, and gaseous above the boiling reference. | Shared phase registry drives the slider, regions and markers. | Evaluated |
| Condition warning | Temperature and pressure define phase behavior; purity/allotropy may matter. | Teaching condition statement | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Ordinary electrical behavior | Metallic conductor | Qualitative bulk behavior; exact resistivity depends on temperature, purity and alloy state. | Measured |
| Conduction model | Collective solid-state electrons | Do not interpret isolated-atom orbital clouds as literal current paths. | Reviewed |
| Surface / compound caveat | Oxides, salts and alloys can behave differently from the pure metal | Material context | Reviewed |
| Engineering values | Condition-dependent | Use condition-specific materials data for engineering calculations. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Common oxidation states | +3, +1; others occur | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | Rh³⁺ | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Rhodium lies in Period 5, Group 9 between ruthenium and palladium. Its d-electron chemistry supports several oxidation states and powerful catalytic surface/complex behavior. | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ¹⁰³Rh | Stable natural isotope | Rhodium is monoisotopic in nature: ¹⁰³Rh accounts for natural rhodium. | Evaluated |
| Radioisotopes | Synthetic isotopes | Radioactive rhodium isotopes are used primarily in research. | Evaluated |
| Natural rhodium | One stable isotope | This simplifies natural-isotope composition compared with many neighboring elements. | Evaluated |
| Teaching nucleus | ¹⁰³Rh · 45 protons + 58 neutrons | Reference isotope used in the nucleus model | Reviewed |
Is Rhodium a solid, liquid or gas? State at temperature
At approximately standard pressure, rhodium is solid below 2236 K, liquid to about 3968 K, and gaseous above the boiling reference.
Where on Earth is Rhodium found or produced?
Who discovered Rhodium, and when?
William Hyde Wollaston discovered rhodium while studying platinum ores.
Rhodium chemistry expanded through complex chemistry, plating and catalysis.
Rhodium became important in emission-control catalysts.
Scarce primary supply and catalyst recycling make rhodium a high-value circular-material story.
From platinum-group ore or recycling to rhodium materials: high-level path
Rhodium is recovered with other platinum-group metals from complex ore and refining streams.
Separation and refining produce high-purity rhodium metal or chemical precursors.
Catalyst and plating industries convert the element into application-specific forms.
Spent automotive and industrial catalysts are important secondary sources; no refining recipe is provided here.
What is rhodium used for?
Catalytic converters
Rhodium catalysts help control nitrogen-oxide emissions.
Chemical catalysis
Rhodium complexes catalyze selected hydrogenation, carbonylation and coupling chemistry.
Plating
Thin rhodium coatings provide reflectivity, hardness and corrosion resistance.
High-temperature components
Rhodium-containing alloys and coatings serve specialized high-temperature or corrosive environments.
Rhodium isotopes and natural abundance
¹⁰³Rh
Stable natural isotopeRhodium is monoisotopic in nature: ¹⁰³Rh accounts for natural rhodium.
Radioisotopes
Synthetic isotopesRadioactive rhodium isotopes are used primarily in research.
Natural rhodium
One stable isotopeThis simplifies natural-isotope composition compared with many neighboring elements.
Five-question Rhodium check
What is rhodium’s symbol?
What structure does rhodium metal use?
What is rhodium plating?
Which use is especially important?
How many stable natural isotopes does Rh have?
Rhodium questions students commonly ask
Each answer starts with the direct fact, then explains the chemistry, evidence or material context so the result is understandable rather than merely memorized.
What is rhodium?
Short answer: Rhodium is chemical element 45, a rare platinum-group transition metal.
Atomic number 45 means every rhodium nucleus contains 45 protons. In the periodic table, Rhodium is classified here as a transition metal · platinum-group metal in Period 5 and Group 9. Rhodium lies in Period 5, Group 9 between ruthenium and palladium. Its d-electron chemistry supports several oxidation states and powerful catalytic surface/complex behavior.
Key point: Rh is element 45; its periodic position and electron structure explain the rest of the page.
Is rhodium a metal?
Short answer: Yes. It is a transition metal and platinum-group metal.
This guide classifies Rhodium as a transition metal · platinum-group metal. Its periodic position is Period 5, d-block, Group 9. Rhodium lies in Period 5, Group 9 between ruthenium and palladium. Its d-electron chemistry supports several oxidation states and powerful catalytic surface/complex behavior.
Key point: Periodic-table classification describes recurring atomic/chemical behavior; it does not make every element in a column physically identical.
What is rhodium used for?
Short answer: Major uses include emission-control catalysts, chemical catalysis and thin protective/decorative plating.
Catalytic converters: Rhodium catalysts help control nitrogen-oxide emissions. Chemical catalysis: Rhodium complexes catalyze selected hydrogenation, carbonylation and coupling chemistry. Searches for “rhodium” often mix chemistry with jewelry price and plating. The science page should first establish Rh as element 45, then explain that plating is a thin rhodium coating and that market price is volatile rather than an intrinsic atomic property.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
What is rhodium plating?
Short answer: A thin coating of rhodium deposited on another material; the plated object is not solid rhodium throughout.
Searches for “rhodium” often mix chemistry with jewelry price and plating. The science page should first establish Rh as element 45, then explain that plating is a thin rhodium coating and that market price is volatile rather than an intrinsic atomic property. Plating Thin rhodium coatings provide reflectivity, hardness and corrosion resistance.
Key point: The pure element, its ions, compounds and alloys are different materials and should not be treated as interchangeable.
Where is rhodium found?
Short answer: It occurs with other platinum-group metals and is recovered from PGM ore/refining streams; recycling is also important.
Rhodium is recovered with other platinum-group metals from complex ore and refining streams. The Geography Explorer keeps natural occurrence separate from resources, industrial production and recycling, because those datasets answer different questions about rhodium.
Key point: Natural occurrence, resources, production and recycling are different geography questions.
Does rhodium tarnish?
Short answer: Rhodium is highly corrosion resistant, one reason it is used as a protective coating.
Plating Thin rhodium coatings provide a bright, hard, corrosion-resistant surface on selected jewelry and components. Pure rhodium is FCC and extremely corrosion resistant.
Key point: The mechanism matters: connect the observed behavior to electron structure, bonding, phase or the specific material form rather than memorizing the result alone.
What is rhodium worth?
Short answer: Its market price is highly volatile. Price is a market variable, not a fixed scientific property of element 45.
Market price changes with supply, demand, purity, form and date. Element Lookup therefore treats price as time-sensitive market context rather than a fixed physical property.
Key point: Price is not an intrinsic scientific constant.
Scientific sources for Rhodium
- Royal Society of Chemistry - Rhodium
- USGS - Platinum-Group Metals
- USGS - Mineral Commodity Summaries 2026
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