Element / isotope identity
Atomic number, isotope identity and discovery evidence are experimentally/evaluatively grounded.
Electron configuration
Very-heavy-element configurations are theory/evaluation-led; ordinary elements use evaluated ground-state references.
Bulk material structure
No macroscopic crystal lattice is asserted.
Phase / density data
Unknown values stay unknown; reported values are tied to the elemental material reference.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Fermium (Fm)
Fermium is element 100. This guide connects its periodic-table identity to evidence-aware structure, isotopes, uses, discovery and the search questions learners actually ask.
Fermium atomic number, mass, electron configuration and key properties
Fermium: quick answers
How many protons, neutrons and electrons does fermium have?
Fermium’s atomic number is 100, so every fermium atom has 100 protons, and a neutral atom also has 100 electrons. Fermium has no stable isotopes, so the neutron count depends on the isotope: fermium-257, featured on this page, has 157 neutrons.
What is the symbol for fermium?
The chemical symbol for fermium is Fm.
Is fermium a solid, liquid or gas at room temperature?
Fermium has only ever been made in tiny amounts, so its state at room temperature has not been observed; it is expected to be a solid metal.
What family (group) is fermium in?
Fermium 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 fermium?
The ground-state electron configuration of fermium is [Rn] 5f¹² 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.
100 protons define fermium.
Ground-state/reference configuration frames atomic behavior; heavy-element predictions remain evidence-labelled.
Periodic position organizes trends without replacing element-specific evidence.
The teaching nucleus is one isotope, not the relative atomic mass.
Measured structures are visualized; unknown bulk structures stay unknown.
Fermium in its period and family
Fermium is element 100 in Period 7. Its f-block/series position provides useful periodic context, but element-specific experimental evidence takes priority over simple trend extrapolation.
Fermium Visual Lab
Explore Fm across the teaching nucleus, isolated-atom orbitals, evidence-aware material structure and temperature/evidence views, then connect those models to uses, isotopes, search-led questions 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.
Fermium in one minute
Atomic number 100 means every fermium nucleus has 100 protons.
The ground-state/reference electron configuration is [Rn] 5f¹² 7s².
The representative teaching isotope is ²⁵⁷Fm.
Fermium is a research-only actinide whose nuclear evidence is far stronger than its macroscopic material evidence. Unknown bulk properties stay unknown.
Material structure status: Bulk crystal structure not experimentally established.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 32 · 30 · 8 · 2 electrons
Displayed orbitals are isolated-atom, nonrelativistic teaching probability models. They are not bulk-band structures, bonding orbitals or direct measured electron-density maps; relativistic effects become especially important for very heavy elements.
No defensible macroscopic crystal lattice is displayed for Fermium. Nuclear/atomic evidence and theory are kept separate from unmeasured bulk material properties.. 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
Displayed orbitals are isolated-atom, nonrelativistic teaching probability models. They are not bulk-band structures, bonding orbitals or direct measured electron-density maps; relativistic effects become especially important for very heavy elements.
Where do I meet fermium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Scientific research only
This context uses Fermium or a fermium-containing material; the element and its compounds/isotopes are kept distinct.
Evidence ladder: nucleus → atom-scale chemistry → unknown bulk material
For scarce synthetic heavy elements, different claims have very different evidence strength.
Nuclear identity
Production/decay evidence establishes the element and specific isotopes.
Fermium in periodic context
Compare nearby or family-related elements without treating a periodic trend as a substitute for element-specific evidence.
| Atomic number | 99 |
|---|---|
| Context | neighbor / series |
| Atomic number | 100 |
|---|---|
| Context | neighbor / series |
| Atomic number | 101 |
|---|---|
| Context | neighbor / series |
Fermium 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 | 100 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | [257] | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Rn] 5f¹² 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 | ²⁵⁷Fm | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Radioactive synthetic actinide produced only in very small quantities | Source-reviewed; see Sources below | Evaluated |
| Density | Unknown | Source-reviewed; see Sources below | Unknown |
| Material / molecular structure | Bulk crystal structure not experimentally established | No defensible macroscopic crystal lattice is displayed for Fermium. Nuclear/atomic evidence and theory are kept separate from unmeasured bulk material properties. | Unknown |
| Classification | Actinide | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | No defensible macroscopic crystal lattice is displayed for Fermium. Nuclear/atomic evidence and theory are kept separate from unmeasured bulk material properties. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 1800 K (reported reference) | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | Unknown | Source-reviewed; see Sources below | Unknown |
| Phase-path context | A melting reference of 1800 K (reported reference) is reported for teaching context, while an ordinary boiling point is not established here. The page does not infer a precise gas transition from theory. | 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 | Fm³⁺ | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Fermium is element 100 in Period 7. Its f-block/series position provides useful periodic context, but element-specific experimental evidence takes priority over simple trend extrapolation. | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ²⁵⁷Fm | Reference teaching isotope | Mass number belongs to a specific isotope and is not the same thing as relative atomic mass. | Evaluated |
| Isotope evidence | Element-specific nuclear context | Half-life and decay properties are isotope-specific; the page does not generalize one isotope to all atoms. | Evaluated |
| Teaching nucleus | ²⁵⁷Fm · 100 protons + 157 neutrons | Reference isotope used in the nucleus model | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Page evidence note | Atomic identity and source-reviewed reference values are separated from predictions. Search demand shapes headings and FAQs but never overrides scientific evidence; unknown bulk structure/density/phase values remain visibly unknown. | Evidence summary for this guide | Reviewed |
| Structure evidence | No defensible macroscopic crystal lattice is displayed for Fermium. Nuclear/atomic evidence and theory are kept separate from unmeasured bulk material properties. | 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 Fermium a solid, liquid or gas? State at temperature
A melting reference of 1800 K (reported reference) is reported for teaching context, while an ordinary boiling point is not established here. The page does not infer a precise gas transition from theory.
Where on Earth is Fermium found or produced?
Who discovered Fermium, and when?
Fermium was identified in debris from the first thermonuclear explosion; the discovery was initially classified.
The element name and discovery story are part of the historical record; search-led questions are answered without turning history into scientific evidence for bulk properties.
Current use is described at the level supported by the element’s availability and evidence, with research-only elements kept research-only.
Research production context: high-level, non-operational
The element is produced or isolated only in specialized research/nuclear settings; this page intentionally omits operational synthesis, target, beam, separation, handling and access instructions.
Experimental identity is established from nuclear decay, spectroscopy and/or atom-scale chemistry appropriate to the element.
Any chemical or material inference is labelled by evidence strength; unmeasured bulk properties are not converted into visual facts.
Research use is described conceptually, with isotope-specific claims kept distinct from the element as a whole.
What is fermium used for?
Scientific research only
Research-only context; no operational production or handling guidance.
Nuclear-structure and heavy-element studies
Research-only context; no operational production or handling guidance.
Fermium isotopes and natural abundance
²⁵⁷Fm
Reference teaching isotopeMass number belongs to a specific isotope and is not the same thing as relative atomic mass.
Isotope evidence
Element-specific nuclear contextHalf-life and decay properties are isotope-specific; the page does not generalize one isotope to all atoms.
Five-question Fermium check
What is Fermium’s atomic number?
Which statement best describes the material evidence for Fermium?
What is the safest rule for Fermium uses?
Fermium 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 fermium?
Short answer: Fermium is chemical element 100, symbol Fm, classified here as actinide.
Atomic number 100 means every fermium nucleus contains 100 protons. In the periodic table, Fermium is classified here as an actinide in Period 7 and Group Actinide. Fermium is element 100 in Period 7. Its f-block/series position provides useful periodic context, but element-specific experimental evidence takes priority over simple trend extrapolation.
Key point: Fm is element 100; its periodic position and electron structure explain the rest of the page.
What is the atomic number of fermium?
Short answer: The atomic number is 100, meaning every fermium nucleus has 100 protons.
Atomic number is defined by proton count, so 100 protons are what make an atom fermium. A neutral fermium atom also has 100 electrons, while isotopes can have different neutron counts without changing the element.
Key point: Atomic number = proton count.
What is the symbol for fermium?
Short answer: The chemical symbol is Fm.
The symbol Fm is the standardized chemical abbreviation for element 100. In a chemical formula, Fm identifies fermium atoms; a compound containing Fm is not automatically the same material as elemental fermium.
Key point: Fm always identifies element 100.
What is fermium used for?
Short answer: Fermium has no use outside scientific research.
Scientific research only: Research-only context; no operational production or handling guidance. Nuclear-structure and heavy-element studies: Research-only context; no operational production or handling guidance. Fermium is a research-only actinide whose nuclear evidence is far stronger than its macroscopic material evidence. Unknown bulk properties stay unknown.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
Who discovered fermium?
Short answer: It was identified by a team including Albert Ghiorso in material from the 1952 thermonuclear test; the finding became public later.
In 1952/1953, fermium was identified in debris from the first thermonuclear explosion; the discovery was initially classified. The element name and discovery story are part of the historical record; search-led questions are answered without turning history into scientific evidence for bulk properties.
Key point: Discovery credit follows the historical evidence and accepted attribution, not just the earliest claim.
What does fermium look like?
Short answer: Only extremely small quantities have been produced, so this guide does not claim a measured macroscopic crystal lattice or ordinary bulk appearance.
The ordinary elemental-material description used here is: Radioactive synthetic actinide produced only in very small quantities. No defensible macroscopic crystal lattice is displayed for Fermium. Nuclear/atomic evidence and theory are kept separate from unmeasured bulk material properties.
Key point: Elemental appearance can differ from the colors of its ions, compounds, oxide films or host materials.
Scientific sources for Fermium
- Royal Society of Chemistry - Fermium
- NIST - Atomic Weights and Isotopic Compositions
- IUPAC - Periodic Table of Elements
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