Element identity
Element 96 and isotope identities are experimental/evaluated.
Melting point
The melting reference is reported/evaluated.
Boiling point
No ordinary boiling point is asserted; no marker is fabricated.
Solid allotropy
Low-temperature dhcp and high-temperature allotropy are acknowledged without an invented precise transition.
Safety boundary
No production, separation, source fabrication, access or handling instructions.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Curium (Cm)
Curium is element 96, a synthetic radioactive actinide named for Marie and Pierre Curie. Its half-filled 5f⁷ shell, isotope science and high-temperature allotropy are known far better than its boiling point—which remains explicitly unknown here.
Curium atomic number, mass, electron configuration and key properties
Curium: quick answers
How many protons, neutrons and electrons does curium have?
Curium’s atomic number is 96, so every curium atom has 96 protons, and a neutral atom also has 96 electrons. Curium has no stable isotopes, so the neutron count depends on the isotope: curium-248, featured on this page, has 152 neutrons.
What is the symbol for curium?
The chemical symbol for curium is Cm.
Is curium a solid, liquid or gas at room temperature?
Curium is a solid at room temperature (about 25 °C).
What family (group) is curium in?
Curium is an actinide, in period 7 (the f-block row shown below the main table) of the periodic table.
What is the electron configuration of curium?
The ground-state electron configuration of curium is [Rn] 5f⁷ 6d¹ 7s².
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.
96 protons define curium.
The ground-state configuration provides the starting point for its chemistry.
Periodic position organizes recurring chemistry and trends.
The teaching nucleus is one isotope, not the relative atomic mass.
Phase boundaries are condition-dependent and evidence-labelled.
Curium in its period and family
Curium lies in the actinide series after americium. The half-filled 5f⁷ configuration is a useful electronic landmark, but radioactive-isotope behavior is a nuclear property, not a consequence of “half-filled stability.”
Curium Visual Lab
Inspect the half-filled 5f shell, a ²⁴⁸Cm teaching nucleus and the low-temperature dhcp metal motif, then use the Evidence Lens to see why melting is known while ordinary boiling behavior is left unknown.
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.
Curium in one minute
Atomic number 96 means 96 protons.
Curium has no stable isotopes.
The standard ground-state reference includes a half-filled 5f⁷ subshell.
Curium melts near 1618 K, but its boiling point is not presented as known.
Curium is an actinide and must not be confused with cerium, a lanthanide.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 32 · 25 · 9 · 2 electrons
The 5f probability model visualizes atomic occupancy. It does not represent radioactive decay, self-heating or the many-body electronic structure of curium metal.
Alpha-curium is commonly described with a double-hexagonal close-packed structure; a higher-temperature FCC form is reported. The transition temperature is not secure enough here for a precise slider marker.. 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 probability model visualizes atomic occupancy. It does not represent radioactive decay, self-heating or the many-body electronic structure of curium metal.
Where do I meet curium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Scientific research
Curium isotopes are studied in actinide chemistry, nuclear structure and materials science.
Half-filled 5f⁷ shell + evidence-limited bulk data
Curium is a strong test of scientific restraint: much atomic/isotope science is known, while some bulk values remain uncertain or unknown.
Half-filled f subshell
The reference ground-state configuration includes 5f7, a useful electronic landmark.
Americium, curium and berkelium
Compare nearby elements to see which patterns repeat and which properties remain element-specific.
| Z | 95 |
|---|---|
| f context | 5f⁷7s² |
| Z | 96 |
|---|---|
| f context | 5f⁷6d¹7s² |
| Z | 97 |
|---|---|
| f context | 5f⁹7s² |
Curium 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 | 96 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | [247] | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Rn] 5f⁷ 6d¹ 7s² | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group Actinide · Period 7 · f-block | Periodic-table placement | Evaluated |
| Electronegativity | Unknown | Source-reviewed; see Sources below | Unknown |
| Reference isotope | ²⁴⁸Cm | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Radioactive silvery metal at 20 °C | Source-reviewed; see Sources below | Evaluated |
| Density | 13.51 g/cm³ | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Curium metal · low-temperature double-hexagonal close-packed teaching reference | Alpha-curium is commonly described with a double-hexagonal close-packed structure; a higher-temperature FCC form is reported. The transition temperature is not secure enough here for a precise slider marker. | Measured |
| Classification | Actinide | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | Alpha-curium is commonly described with a double-hexagonal close-packed structure; a higher-temperature FCC form is reported. The transition temperature is not secure enough here for a precise slider marker. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 1618 K | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | Unknown | Source-reviewed; see Sources below | Unknown |
| Phase-path context | The ordinary teaching track shows solid curium up to the measured melting reference near 1618 K and liquid above it within the displayed range. A high-temperature solid allotrope is known, but no precise transition marker is asserted here. The boiling point is unknown, so no invented liquid→gas boundary is shown. | 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 (dominant), +4 also known | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | Cm³⁺ is the most common solution-state ion; +4 also occurs | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Curium lies in the actinide series after americium. The half-filled 5f⁷ configuration is a useful electronic landmark, but radioactive-isotope behavior is a nuclear property, not a consequence of “half-filled stability.” | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ²⁴³Cm | Radioactive · t½ ≈29.1 years | One of several important curium isotopes used in research. | Evaluated |
| ²⁴⁴Cm | Radioactive · t½ ≈18.1 years | A relatively strong alpha emitter used in specialized controlled contexts. | Evaluated |
| ²⁴⁸Cm | Radioactive · t½ ≈348,000 years | Reference teaching nucleus: 96 protons and 152 neutrons; comparatively long-lived among curium isotopes. | Evaluated |
| ²⁴⁷Cm | Radioactive · t½ ≈15.6 million years | The longest-lived known curium isotope, useful for nuclear-science context. | Evaluated |
| Teaching nucleus | ²⁴⁸Cm · 96 protons + 152 neutrons | Reference isotope used in the nucleus model | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Page evidence note | Identity, isotope half-lives, density and melting point are evaluated/measured. The dhcp structure is a reviewed teaching reference. The boiling point remains unknown and the phase model intentionally contains no fabricated boiling marker. | Evidence summary for this guide | Reviewed |
| Structure evidence | Alpha-curium is commonly described with a double-hexagonal close-packed structure; a higher-temperature FCC form is reported. The transition temperature is not secure enough here for a precise slider marker. | 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 | 3 primary/reference links listed below | Open the Sources section for the actual references. | Reviewed |
Is Curium a solid, liquid or gas? State at temperature
The ordinary teaching track shows solid curium up to the measured melting reference near 1618 K and liquid above it within the displayed range. A high-temperature solid allotrope is known, but no precise transition marker is asserted here. The boiling point is unknown, so no invented liquid→gas boundary is shown.
Where on Earth is Curium found or produced?
Who discovered Curium, and when?
Glenn Seaborg, Ralph James and Albert Ghiorso produced curium at Berkeley during transuranium-element research.
The element was named for Marie and Pierre Curie, pioneers of radioactivity research.
Different curium isotopes enabled nuclear-structure, chemistry and space-instrument research.
Curium remains a controlled research material with no ordinary consumer role.
Curium research context: deliberately non-operational
Curium is synthetic and exists only in radioactive forms; natural-resource maps are therefore inappropriate.
Licensed research facilities study minute quantities using specialized radiological containment and instrumentation.
Production, irradiation, separation and source-fabrication procedures are intentionally excluded.
Public educational discussion focuses on identity, electronic structure, isotope half-lives, measured properties and discovery history.
What is curium used for?
Actinide research
Curium is used to investigate heavy-element chemistry and nuclear structure.
Specialized sources
Selected curium isotopes have been used in tightly controlled source/instrument contexts.
Space science history
Curium has appeared in selected space-science instrument/power applications.
No ordinary consumer use
Radioactivity and scarcity restrict curium to specialized regulated settings.
Curium isotopes and natural abundance
²⁴³Cm
Radioactive · t½ ≈29.1 yearsOne of several important curium isotopes used in research.
²⁴⁴Cm
Radioactive · t½ ≈18.1 yearsA relatively strong alpha emitter used in specialized controlled contexts.
²⁴⁸Cm
Radioactive · t½ ≈348,000 yearsReference teaching nucleus: 96 protons and 152 neutrons; comparatively long-lived among curium isotopes.
²⁴⁷Cm
Radioactive · t½ ≈15.6 million yearsThe longest-lived known curium isotope, useful for nuclear-science context.
Five-question Curium check
Atomic number?
Curium vs cerium?
Stable isotopes?
Boiling point shown?
Electronic feature?
Curium 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 curium’s atomic number?
Short answer: 96.
Atomic number is defined by proton count, so 96 protons are what make an atom curium. A neutral curium atom also has 96 electrons, while isotopes can have different neutron counts without changing the element.
Key point: Atomic number = proton count.
Is curium the same as cerium?
Short answer: No. Curium is Cm, element 96, an actinide; cerium is Ce, element 58, a lanthanide.
Curium is not cerium. Curium (Cm, 96) is a radioactive actinide; cerium (Ce, 58) is a lanthanide. Similar names do not imply similar position, isotope behavior or everyday uses. Actinide research Curium is used to investigate heavy-element chemistry and nuclear structure.
Key point: The pure element, its ions, compounds and alloys are different materials and should not be treated as interchangeable.
What is curium’s electron configuration?
Short answer: [Rn] 5f⁷ 6d¹ 7s² is the standard reference.
The neutral-atom ground-state reference used on this page is [Rn] 5f⁷ 6d¹ 7s². This is an isolated-atom reference: bonding and ion formation can change which outer electrons are present or chemically active. The listed common oxidation-state context is +3 (dominant), +4 also known, which helps connect the atomic configuration to ordinary chemistry without treating electron counting as a single universal rule.
Key point: Electron configuration is a ground-state atomic reference, not a literal picture of every compound.
Does curium have stable isotopes?
Short answer: No.
²⁴³Cm: Radioactive · t½ ≈29.1 years: One of several important curium isotopes used in research. ²⁴⁴Cm: Radioactive · t½ ≈18.1 years: A relatively strong alpha emitter used in specialized controlled contexts.
Key point: Radioactivity is isotope-specific; do not apply one isotope’s nuclear behavior to every atom of the element.
What is curium’s boiling point?
Short answer: It is not treated as reliably known here, so Element Lookup leaves it unknown rather than inventing a value.
The ordinary teaching track shows solid curium up to the measured melting reference near 1618 K and liquid above it within the displayed range. A high-temperature solid allotrope is known, but no precise transition marker is asserted here. The boiling point is unknown, so no invented liquid→gas boundary is shown.
Key point: Phase statements need temperature, pressure and evidence context.
What is curium used for?
Short answer: Primarily specialized scientific research and tightly controlled source/instrument contexts.
Actinide research: Curium is used to investigate heavy-element chemistry and nuclear structure. Specialized sources: Selected curium isotopes have been used in tightly controlled source/instrument contexts. Curium is not cerium. Curium (Cm, 96) is a radioactive actinide; cerium (Ce, 58) is a lanthanide. Similar names do not imply similar position, isotope behavior or everyday uses.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
Scientific sources for Curium
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