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.
Mendelevium (Md)
Mendelevium is element 101. This guide connects its periodic-table identity to evidence-aware structure, isotopes, uses, discovery and the search questions learners actually ask.
Mendelevium atomic number, mass, electron configuration and key properties
Mendelevium: quick answers
How many protons, neutrons and electrons does mendelevium have?
Mendelevium’s atomic number is 101, so every mendelevium atom has 101 protons, and a neutral atom also has 101 electrons. Mendelevium has no stable isotopes, so the neutron count depends on the isotope: mendelevium-258, featured on this page, has 157 neutrons.
What is the symbol for mendelevium?
The chemical symbol for mendelevium is Md.
Is mendelevium a solid, liquid or gas at room temperature?
Mendelevium 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 mendelevium in?
Mendelevium 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 mendelevium?
The ground-state electron configuration of mendelevium is [Rn] 5f¹³ 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.
101 protons define mendelevium.
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.
Mendelevium in its period and family
Mendelevium is element 101 in Period 7. Its f-block/series position provides useful periodic context, but element-specific experimental evidence takes priority over simple trend extrapolation.
Mendelevium Visual Lab
Explore Md 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.
Mendelevium in one minute
Atomic number 101 means every mendelevium nucleus has 101 protons.
The ground-state/reference electron configuration is [Rn] 5f¹³ 7s².
The representative teaching isotope is ²⁵⁸Md.
Mendelevium is element 101 and a search-heavy naming story: it honours Dmitri Mendeleev. The page separates measured nuclear/chemical evidence from unobserved bulk appearance and crystal structure.
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 · 31 · 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 Mendelevium. 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 mendelevium?
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 Mendelevium or a mendelevium-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.
Mendelevium in periodic context
Compare nearby or family-related elements without treating a periodic trend as a substitute for element-specific evidence.
| Atomic number | 100 |
|---|---|
| Context | neighbor / series |
| Atomic number | 101 |
|---|---|
| Context | neighbor / series |
| Atomic number | 102 |
|---|---|
| Context | neighbor / series |
Mendelevium 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 | 101 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | [258] | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Rn] 5f¹³ 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 | ²⁵⁸Md | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Radioactive synthetic actinide observed only in atom-scale 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 Mendelevium. 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 Mendelevium. 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 | 1100 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 1100 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, +2 | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | Md³⁺ | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Mendelevium is element 101 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 |
|---|---|---|---|
| ²⁵⁸Md | 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 | ²⁵⁸Md · 101 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 Mendelevium. 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 Mendelevium a solid, liquid or gas? State at temperature
A melting reference of 1100 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 Mendelevium found or produced?
Who discovered Mendelevium, and when?
Albert Ghiorso, Glenn Seaborg and colleagues produced element 101 at Berkeley and named it for Dmitri Mendeleev.
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 mendelevium used for?
Scientific research only
Research-only context; no operational production or handling guidance.
Actinide chemistry studies at atom-scale quantities
Research-only context; no operational production or handling guidance.
Mendelevium isotopes and natural abundance
²⁵⁸Md
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 Mendelevium check
What is Mendelevium’s atomic number?
Which statement best describes the material evidence for Mendelevium?
What is the safest rule for Mendelevium uses?
Mendelevium 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 the atomic number of mendelevium?
Short answer: The atomic number is 101, meaning every mendelevium nucleus has 101 protons.
Atomic number is defined by proton count, so 101 protons are what make an atom mendelevium. A neutral mendelevium atom also has 101 electrons, while isotopes can have different neutron counts without changing the element.
Key point: Atomic number = proton count.
What is the symbol for mendelevium?
Short answer: The chemical symbol is Md.
The symbol Md is the standardized chemical abbreviation for element 101. In a chemical formula, Md identifies mendelevium atoms; a compound containing Md is not automatically the same material as elemental mendelevium.
Key point: Md always identifies element 101.
What is mendelevium?
Short answer: Mendelevium is element 101, symbol Md, a synthetic radioactive actinide.
Atomic number 101 means every mendelevium nucleus contains 101 protons. In the periodic table, Mendelevium is classified here as an actinide in Period 7 and Group Actinide. Mendelevium is element 101 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: Md is element 101; its periodic position and electron structure explain the rest of the page.
What element was named after Mendeleev?
Short answer: Mendelevium was named in honour of Dmitri Mendeleev, whose periodic-table work transformed chemistry.
In 1955, Albert Ghiorso, Glenn Seaborg and colleagues produced element 101 at Berkeley and named it for Dmitri Mendeleev. 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: Element names record scientific history; the name itself does not determine the element’s chemistry.
What is mendelevium used for?
Short answer: Mendelevium has no commercial use; it is used only in scientific research.
Scientific research only: Research-only context; no operational production or handling guidance. Actinide chemistry studies at atom-scale quantities: Research-only context; no operational production or handling guidance. Mendelevium is element 101 and a search-heavy naming story: it honours Dmitri Mendeleev. The page separates measured nuclear/chemical evidence from unobserved bulk appearance and crystal structure.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
What does mendelevium look like?
Short answer: It is expected to be metallic, but only atom-scale quantities have been produced. No ordinary macroscopic sample or measured bulk crystal structure is presented here.
The ordinary elemental-material description used here is: Radioactive synthetic actinide observed only in atom-scale quantities. No defensible macroscopic crystal lattice is displayed for Mendelevium. 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 Mendelevium
- Royal Society of Chemistry - Mendelevium
- NIST - Atomic Weights and Isotopic Compositions
- IUPAC - Periodic Table of Elements
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