Element identity
Element 61 and isotope identities are established.
No stable isotopes
All promethium isotopes are radioactive.
Phase references
Reference melting/boiling values are used cautiously for scarce radioactive material.
Solid structure
Close-packed metallic reference is shown as reviewed; detailed allotrope transitions are not fabricated.
Safety boundary
No production, source fabrication or handling guidance.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Promethium (Pm)
Promethium is element 61, a radioactive lanthanide with no stable isotopes. Minute natural quantities can arise from nuclear processes, but useful material is produced for research and specialized applications; its chemistry is dominated by Pm³⁺.
Promethium atomic number, mass, electron configuration and key properties
Promethium: quick answers
How many protons, neutrons and electrons does promethium have?
Promethium’s atomic number is 61, so every promethium atom has 61 protons, and a neutral atom also has 61 electrons. Promethium has no stable isotopes, so the neutron count depends on the isotope: promethium-145, featured on this page, has 84 neutrons.
What is the symbol for promethium?
The chemical symbol for promethium is Pm.
Is promethium a solid, liquid or gas at room temperature?
Promethium is a solid at room temperature (about 25 °C).
What family (group) is promethium in?
Promethium is a lanthanide, in period 6 (the f-block row shown below the main table) of the periodic table.
What is the electron configuration of promethium?
The ground-state electron configuration of promethium is [Xe] 4f⁵ 6s².
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.
61 protons define promethium.
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.
Promethium in its period and family
Promethium lies between neodymium and samarium in the lanthanide series. Its [Xe] 4f⁵6s² reference configuration and +3 chemistry fit the broader rare-earth pattern.
Promethium Visual Lab
Explore Pm 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.
Promethium in one minute
Atomic number 61 means 61 protons.
Promethium has no stable isotopes.
Pm³⁺ is the dominant ordinary chemical state.
Minute natural promethium can occur transiently, but there is no mineable natural resource.
¹⁴⁵Pm is among the longest-lived promethium isotopes, while ¹⁴⁷Pm is important in application history.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 23 · 8 · 2 electrons
The 5f/6s cloud views are isolated-atom teaching models. Lanthanide bonding, ions and solid metal involve many-electron states beyond these shapes.
Metallic promethium is reported in close-packed hexagonal allotrope contexts. The viewer uses a dhcp teaching motif and labels the evidence as reviewed because bulk experimental literature is sparse compared with common metals.. 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
The 5f/6s cloud views are isolated-atom teaching models. Lanthanide bonding, ions and solid metal involve many-electron states beyond these shapes.
Where do I meet promethium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Radioisotope research
Promethium isotopes are studied in nuclear and lanthanide chemistry.
No stable isotopes → Pm3+ lanthanide chemistry → transient inventories
Promethium is a missing natural-series link that becomes chemically ordinary only after its nuclear instability is acknowledged.
No stable isotope
Every promethium isotope is radioactive.
Neodymium, promethium and samarium
Promethium sits between ordinary natural lanthanides yet has no stable isotope, making nuclear stability the standout discontinuity.
| Chemistry | mostly +3 |
|---|---|
| Natural | yes |
| Chemistry | mostly +3 |
|---|---|
| Stable isotope | none |
| Chemistry | mostly +3 |
|---|---|
| Natural | yes |
Promethium 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 | 61 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | [145] | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Xe] 4f⁵ 6s² | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group Lanthanide · Period 6 · f-block | Periodic-table placement | Evaluated |
| Electronegativity | Unknown / not conventionally assigned | Source-reviewed; see Sources below | Evaluated |
| Reference isotope | ¹⁴⁵Pm | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Radioactive lanthanide metal; no stable isotopes | Source-reviewed; see Sources below | Evaluated |
| Density | 7.26 g/cm³ | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Reported double-hexagonal close-packed metal | Metallic promethium is reported in close-packed hexagonal allotrope contexts. The viewer uses a dhcp teaching motif and labels the evidence as reviewed because bulk experimental literature is sparse compared with common metals. | Measured |
| Classification | Radioactive lanthanide | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | Metallic promethium is reported in close-packed hexagonal allotrope contexts. The viewer uses a dhcp teaching motif and labels the evidence as reviewed because bulk experimental literature is sparse compared with common metals. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 1315 K | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | 3273 K | Source-reviewed; see Sources below | Evaluated |
| Phase-path context | Using reviewed reference values, promethium metal is treated as solid below about 1315 K, liquid to about 3273 K, and gaseous above. Detailed allotrope transitions are not invented. | 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 |
|---|---|---|---|
| Common oxidation states | +3 | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | Pm³⁺ | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Promethium lies between neodymium and samarium in the lanthanide series. Its [Xe] 4f⁵6s² reference configuration and +3 chemistry fit the broader rare-earth pattern. | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ¹⁴⁵Pm | Radioactive · ~17.7 y | Among the longest-lived promethium isotopes and the reference teaching nucleus. | Evaluated |
| ¹⁴⁷Pm | Radioactive · ~2.62 y | Historically important beta-emitting isotope. | Evaluated |
| Promethium isotope context | No stable isotopes | All promethium isotopes are radioactive. | Evaluated |
| Teaching nucleus | ¹⁴⁵Pm · 61 protons + 84 neutrons | Reference isotope used in the nucleus model | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Page evidence note | Element/isotope identity and reference atomic values are evaluated. Bulk phase values and close-packed metal structure are source-reviewed but experimental literature is sparse; no detailed allotrope transition is fabricated. | Evidence summary for this guide | Reviewed |
| Structure evidence | Metallic promethium is reported in close-packed hexagonal allotrope contexts. The viewer uses a dhcp teaching motif and labels the evidence as reviewed because bulk experimental literature is sparse compared with common metals. | Measured structure, labelled schematic, prediction or explicit unknown as applicable. | Reviewed |
| Map evidence rule | Real pins are reviewed examples; conceptual layers are used when pins would mislead. | Geography Explorer 2.0 | Reviewed |
| Source set | 2 primary/reference links listed below | Open the Sources section for the actual references. | Reviewed |
Is Promethium a solid, liquid or gas? State at temperature
Using reviewed reference values, promethium metal is treated as solid below about 1315 K, liquid to about 3273 K, and gaseous above. Detailed allotrope transitions are not invented.
Where on Earth is Promethium found or produced?
Who discovered Promethium, and when?
Jacob Marinsky, Lawrence Glendenin and Charles Coryell identified element 61 among fission products at Oak Ridge.
The name promethium was announced, invoking the mythic Prometheus.
Promethium isotopes were investigated for beta-source and specialized power applications.
Promethium remains a research and specialty radioisotope element with no stable isotope.
Promethium: from nuclear origin to research material — non-operational overview
Promethium isotopes arise through nuclear transformations; operational production conditions are outside this guide.
Chemical separation in specialist facilities can isolate promethium compounds, but no procedural parameters are provided.
Most ordinary chemistry involves Pm³⁺, allowing comparison across the lanthanides.
Radioactive decay continually limits inventory and shapes all applications.
What is promethium used for?
Nuclear research
Promethium isotopes support studies of decay and fission products.
Lanthanide chemistry
Pm³⁺ provides a radioactive test point in rare-earth trends.
Historical beta sources
¹⁴⁷Pm has served in specialized beta-powered or luminescent device contexts.
Measurement research
Promethium sources have supported selected thickness and instrumentation applications under controlled conditions.
Promethium isotopes and natural abundance
¹⁴⁵Pm
Radioactive · ~17.7 yAmong the longest-lived promethium isotopes and the reference teaching nucleus.
¹⁴⁷Pm
Radioactive · ~2.62 yHistorically important beta-emitting isotope.
Promethium isotope context
No stable isotopesAll promethium isotopes are radioactive.
Five-question Promethium check
What is promethium’s atomic number?
Does promethium have a stable isotope?
What is its dominant chemical ion?
Can promethium occur naturally at all?
What should the guide avoid?
Promethium 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 promethium?
Short answer: Promethium is radioactive lanthanide element 61, symbol Pm.
Atomic number 61 means every promethium nucleus contains 61 protons. In the periodic table, Promethium is classified here as a radioactive lanthanide in Period 6 and Group Lanthanide. Promethium lies between neodymium and samarium in the lanthanide series. Its [Xe] 4f⁵6s² reference configuration and +3 chemistry fit the broader rare-earth pattern.
Key point: Pm is element 61; its periodic position and electron structure explain the rest of the page.
Is promethium a metal?
Short answer: Yes. It is a lanthanide metal.
This guide classifies Promethium as a radioactive lanthanide. Its periodic position is Period 6, f-block, Group Lanthanide. Promethium lies between neodymium and samarium in the lanthanide series. Its [Xe] 4f⁵6s² reference configuration and +3 chemistry fit the broader rare-earth pattern.
Key point: Periodic-table classification describes recurring atomic/chemical behavior; it does not make every element in a column physically identical.
Is promethium radioactive?
Short answer: Yes. It has no stable isotopes.
¹⁴⁵Pm: Radioactive · ~17.7 y: Among the longest-lived promethium isotopes and the reference teaching nucleus. ¹⁴⁷Pm: Radioactive · ~2.62 y: Historically important beta-emitting isotope.
Key point: Radioactivity is isotope-specific; do not apply one isotope’s nuclear behavior to every atom of the element.
Where is promethium found?
Short answer: Only minute transient natural quantities occur from nuclear processes; practical material is associated with controlled production, not mining.
Promethium isotopes arise through nuclear transformations; operational production conditions are outside this guide. “Does promethium occur naturally?” deserves more than yes/no. No primordial stable promethium survives on Earth, but minute transient quantities can arise from uranium fission and related nuclear processes. That is different from having a mineable natural promethium resource.
Key point: Natural occurrence, resources, production and recycling are different geography questions.
What is promethium used for?
Short answer: Mostly research and specialized radioisotope applications; ¹⁴⁷Pm has historical beta-source uses.
Nuclear research: Promethium isotopes support studies of decay and fission products. Lanthanide chemistry: Pm³⁺ provides a radioactive test point in rare-earth trends. “Does promethium occur naturally?” deserves more than yes/no. No primordial stable promethium survives on Earth, but minute transient quantities can arise from uranium fission and related nuclear processes. That is different from having a mineable natural promethium resource.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
Who discovered promethium?
Short answer: Marinsky, Glendenin and Coryell identified it in 1945 from fission products.
In 1945, Jacob Marinsky, Lawrence Glendenin and Charles Coryell identified element 61 among fission products at Oak Ridge. In 1947, The name promethium was announced, invoking the mythic Prometheus.
Key point: Discovery credit follows the historical evidence and accepted attribution, not just the earliest claim.
What does promethium look like?
Short answer: It is described as a metallic lanthanide, but the page avoids overstating appearance because ordinary bulk samples are scarce and radioactive.
The ordinary elemental-material description used here is: Radioactive lanthanide metal; no stable isotopes. Metallic promethium is reported in close-packed hexagonal allotrope contexts. The viewer uses a dhcp teaching motif and labels the evidence as reviewed because bulk experimental literature is sparse compared with common metals.
Key point: Elemental appearance can differ from the colors of its ions, compounds, oxide films or host materials.
Scientific sources for Promethium
Questions to ask next about Promethium
A good element lesson should lead to the next useful question, not end after a list of facts.
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