Element / phase data
Atomic and bulk-metal reference values are evaluated.
No stable isotopes
All known technetium isotopes are radioactive.
99mTc vs 99Tc
Metastable and ground states are explicitly separated by half-life/use context.
Natural trace
Trace fission-related natural occurrence is acknowledged without implying a resource.
Medical context
Diagnostic context is non-operational; no production/dose/handling guidance.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Technetium (Tc)
Technetium is element 43, the first element produced artificially before its trace natural occurrence was established. Every technetium isotope is radioactive, and the key learning distinction is between long-lived ⁹⁹Tc and short-lived metastable ⁹⁹ᵐTc used in diagnostic nuclear medicine.
Technetium atomic number, mass, electron configuration and key properties
Technetium: quick answers
How many protons, neutrons and electrons does technetium have?
Technetium’s atomic number is 43, so every technetium atom has 43 protons, and a neutral atom also has 43 electrons. Technetium has no stable isotopes, so the neutron count depends on the isotope: technetium-99, featured on this page, has 56 neutrons.
What is the symbol for technetium?
The chemical symbol for technetium is Tc.
Is technetium a solid, liquid or gas at room temperature?
Technetium is a solid at room temperature (about 25 °C).
What family (group) is technetium in?
Technetium is a transition metal, in group 7, period 5 of the periodic table.
What is the electron configuration of technetium?
The ground-state electron configuration of technetium is [Kr] 4d⁵ 5s².
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.
43 protons define technetium.
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.
Technetium in its period and family
Technetium sits in Group 7 between molybdenum and ruthenium, below manganese. Its 4d⁵5s² reference configuration supports a wide range of oxidation states, including important +7 chemistry.
Technetium Visual Lab
Explore Tc 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.
Technetium in one minute
Atomic number 43 means 43 protons.
Technetium has no stable isotopes.
⁹⁹Tc and ⁹⁹ᵐTc are different nuclear states with radically different half-lives.
Trace technetium can occur naturally from uranium fission, despite its primarily synthetic association.
The page gives medical context without production, dosing or handling instructions.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 13 · 2 electrons
Representative 4d/5s clouds are isolated-atom models; they do not describe Tc complexes, metal bands or nuclear metastable states.
Bulk technetium metal has an HCP structure. The viewer is a conventional hexagonal teaching model; radioactive identity is a nuclear property and does not erase ordinary solid-state structure.. 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/5s clouds are isolated-atom models; they do not describe Tc complexes, metal bands or nuclear metastable states.
Where do I meet technetium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Diagnostic imaging
⁹⁹ᵐTc is widely used as a gamma-emitting tracer in diagnostic nuclear medicine.
No stable isotope → 99mTc imaging clock → long-lived 99Tc
Technetium’s core lesson is isotope and nuclear-state identity: the same proton count can lead to radically different practical timescales.
Z = 43
Every technetium isotope is radioactive.
Manganese, technetium and rhenium
Group 7 connects rich oxidation-state chemistry across 3d, 4d and 5d metals, while nuclear stability changes dramatically at technetium.
| Evidence | stable natural element |
|---|---|
| High state | +7 |
| Evidence | no stable isotopes |
|---|---|
| High state | +7 |
| Evidence | natural isotopes |
|---|---|
| High state | +7 |
Technetium 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 | 43 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | [98] | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Kr] 4d⁵ 5s² | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group 7 · Period 5 · d-block | Periodic-table placement | Evaluated |
| Electronegativity | 2.10 | Source-reviewed; see Sources below | Evaluated |
| Reference isotope | ⁹⁹Tc | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Silvery-gray radioactive metal; no stable isotopes | Source-reviewed; see Sources below | Evaluated |
| Density | 11 g/cm³ | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Hexagonal close-packed | Bulk technetium metal has an HCP structure. The viewer is a conventional hexagonal teaching model; radioactive identity is a nuclear property and does not erase ordinary solid-state structure. | Measured |
| Classification | Radioactive transition metal | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | Bulk technetium metal has an HCP structure. The viewer is a conventional hexagonal teaching model; radioactive identity is a nuclear property and does not erase ordinary solid-state structure. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 2430 K | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | 4535 K | Source-reviewed; see Sources below | Evaluated |
| Phase-path context | At approximately standard pressure, technetium metal is solid below about 2430 K, liquid to about 4535 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 |
|---|---|---|---|
| Common oxidation states | +7 common; multiple lower states occur | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | TcO₄⁻ context | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Technetium sits in Group 7 between molybdenum and ruthenium, below manganese. Its 4d⁵5s² reference configuration supports a wide range of oxidation states, including important +7 chemistry. | Element-specific interpretation | Reviewed |
| Chemistry caution | Elemental form, ions and compounds are distinct chemical objects. | Interpretive teaching rule | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| ⁹⁹ᵐTc | Metastable state · ~6 h half-life | Widely used in diagnostic imaging; decays to ⁹⁹Tc. | Evaluated |
| ⁹⁹Tc | Long-lived ground state · ~2.1 × 10⁵ y | Important fission product and reference teaching nucleus. | Evaluated |
| ⁹⁸Tc | Long-lived radioisotope | One of technetium’s longest-lived isotopes; no technetium isotope is stable. | Evaluated |
| Teaching nucleus | ⁹⁹Tc · 43 protons + 56 neutrons | Reference isotope used in the nucleus model | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Page evidence note | Atomic and phase references are evaluated. The HCP metal structure is separate from isotope/nuclear-state identity. Medical and production context is intentionally non-operational. | Evidence summary for this guide | Reviewed |
| Structure evidence | Bulk technetium metal has an HCP structure. The viewer is a conventional hexagonal teaching model; radioactive identity is a nuclear property and does not erase ordinary solid-state structure. | 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 Technetium a solid, liquid or gas? State at temperature
At approximately standard pressure, technetium metal is solid below about 2430 K, liquid to about 4535 K, and gaseous above the boiling reference.
Where on Earth is Technetium found or produced?
Who discovered Technetium, and when?
Carlo Perrier and Emilio Segrè identified element 43 in molybdenum material that had been irradiated in a cyclotron.
The name technetium, from Greek for “artificial,” was adopted.
⁹⁹ᵐTc became a cornerstone of diagnostic nuclear medicine.
Trace natural technetium and long-lived ⁹⁹Tc are studied in nuclear and environmental contexts.
How technetium knowledge is used: high-level nuclear and chemical context
Technetium isotopes arise in nuclear processes; operational production parameters are outside this guide.
Nuclear state and isotope identity determine half-life and radiation behavior.
Chemical coordination allows technetium tracers to be incorporated into diagnostic compounds under regulated specialist practice.
Long-lived ⁹⁹Tc is treated separately in environmental and waste-form science.
What is technetium used for?
Diagnostic nuclear medicine
⁹⁹ᵐTc supports many regulated imaging procedures through labeled radiopharmaceuticals.
Tracer chemistry
Technetium isotopes are used to study chemical and biological distribution.
Nuclear research
Its isotopes help investigate fission products and decay.
Materials/environment research
⁹⁹Tc chemistry matters in long-term nuclear-waste and environmental studies.
Technetium isotopes and natural abundance
⁹⁹ᵐTc
Metastable state · ~6 h half-lifeWidely used in diagnostic imaging; decays to ⁹⁹Tc.
⁹⁹Tc
Long-lived ground state · ~2.1 × 10⁵ yImportant fission product and reference teaching nucleus.
⁹⁸Tc
Long-lived radioisotopeOne of technetium’s longest-lived isotopes; no technetium isotope is stable.
Five-question Technetium check
What is technetium’s atomic number?
Are any technetium isotopes stable?
Which state is widely used in imaging?
Is trace natural Tc possible?
What is the bulk metal structure?
Technetium 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 technetium?
Short answer: Technetium is radioactive chemical element 43, a transition metal with no stable isotopes.
Atomic number 43 means every technetium nucleus contains 43 protons. In the periodic table, Technetium is classified here as a radioactive transition metal in Period 5 and Group 7. Technetium sits in Group 7 between molybdenum and ruthenium, below manganese. Its 4d⁵5s² reference configuration supports a wide range of oxidation states, including important +7 chemistry.
Key point: Tc is element 43; its periodic position and electron structure explain the rest of the page.
Why is technetium radioactive?
Short answer: No combination of 43 protons and known neutron counts produces a stable technetium nucleus.
⁹⁹ᵐTc: Metastable state · ~6 h half-life: Widely used in diagnostic imaging; decays to ⁹⁹Tc. ⁹⁹Tc: Long-lived ground state · ~2.1 × 10⁵ y: Important fission product and reference teaching nucleus.
Key point: Radioactivity is isotope-specific; do not apply one isotope’s nuclear behavior to every atom of the element.
Is technetium naturally occurring?
Short answer: It is primarily associated with artificial production, but trace technetium can occur naturally through uranium fission and related nuclear processes.
Trace technetium can occur naturally from uranium fission, despite its primarily synthetic association. Trace natural occurrence Tiny quantities can arise naturally through spontaneous fission and related nuclear processes.
Key point: Use the direct answer together with the material, isotope and evidence context shown elsewhere on the page.
What is technetium used for?
Short answer: The best-known use is ⁹⁹ᵐTc in diagnostic nuclear medicine; technetium also has tracer and nuclear-research roles.
Diagnostic nuclear medicine: ⁹⁹ᵐTc supports many regulated imaging procedures through labeled radiopharmaceuticals. Tracer chemistry: Technetium isotopes are used to study chemical and biological distribution. “Technetium-99” and “technetium-99m” are not interchangeable labels. ⁹⁹ᵐTc is a metastable nuclear state with a roughly six-hour half-life used for imaging; ⁹⁹Tc is the much longer-lived ground state with a half-life of about 2.1 × 10⁵ years.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
What is the difference between Tc-99 and Tc-99m?
Short answer: ⁹⁹ᵐTc is a short-lived metastable nuclear state used for imaging; ⁹⁹Tc is the much longer-lived ground state.
“Technetium-99” and “technetium-99m” are not interchangeable labels. ⁹⁹ᵐTc is a metastable nuclear state with a roughly six-hour half-life used for imaging; ⁹⁹Tc is the much longer-lived ground state with a half-life of about 2.1 × 10⁵ years. Diagnostic nuclear medicine ⁹⁹ᵐTc supports many regulated imaging procedures through labeled radiopharmaceuticals.
Key point: The pure element, its ions, compounds and alloys are different materials and should not be treated as interchangeable.
Who discovered technetium?
Short answer: Carlo Perrier and Emilio Segrè identified element 43 in 1937.
In 1937, Carlo Perrier and Emilio Segrè identified element 43 in molybdenum material that had been irradiated in a cyclotron. In 1947, The name technetium, from Greek for “artificial,” was adopted.
Key point: Discovery credit follows the historical evidence and accepted attribution, not just the earliest claim.
What is technetium’s electron configuration?
Short answer: [Kr] 4d⁵ 5s².
The neutral-atom ground-state reference used on this page is [Kr] 4d⁵ 5s². 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 +7 common; multiple lower states occur, 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.
Scientific sources for Technetium
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