Atomic / phase data
Reference values are evaluated.
FCC structure
Ambient-pressure FCC structure is used.
Isotope context
Stable isotopes and radiogenic 87Sr context are established.
Geography
Celestite-production points use dated commodity context.
The lens describes evidence status, not confidence theatre. “Unknown” is kept unknown, and teaching schematics are not presented as direct measurements.
Strontium (Sr)
Strontium is element 38, a Group 2 metal best known for Sr²⁺ chemistry, brilliant red emission and isotope applications. Its story links electron structure to fireworks, ferrite magnets, geology and radiogenic ⁸⁷Sr.
Strontium atomic number, mass, electron configuration and key properties
Strontium: quick answers
How many protons, neutrons and electrons does strontium have?
Strontium’s atomic number is 38, so every strontium atom has 38 protons, and a neutral atom also has 38 electrons. Its most common natural isotope, strontium-88, has 50 neutrons (other isotopes have different neutron counts).
What is the symbol for strontium?
The chemical symbol for strontium is Sr.
Is strontium a solid, liquid or gas at room temperature?
Strontium is a solid at room temperature (about 25 °C).
What family (group) is strontium in?
Strontium is an alkaline earth metal, in group 2, period 5 of the periodic table.
How many valence electrons does strontium have?
Strontium has 2 valence electrons, the electrons in its outer shell, which matches its position in group 2.
What is the electron configuration of strontium?
The ground-state electron configuration of strontium is [Kr] 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.
38 protons define strontium.
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.
Strontium in its period and family
Strontium is the Period 5 member of Group 2, below calcium and above barium. Its two outer 5s electrons underpin common +2 chemistry.
Strontium Visual Lab
Compare Sr with Sr²⁺, inspect the 5s electron probability model, rotate the FCC teaching structure, and explore red emission, celestite supply and the ⁸⁷Rb→⁸⁷Sr geochemical clock.
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.
Strontium in one minute
Atomic number 38 means 38 protons.
Neutral strontium ends in 5s² and commonly forms Sr²⁺.
Strontium compounds can produce a strong red flame/emission color.
Natural strontium includes four stable isotopes.
⁸⁷Sr can include radiogenic contribution from ⁸⁷Rb decay, making isotope ratios useful in geology.
Shell rings organize electron counts. They are not electron trajectories or orbital shapes.
2 · 8 · 18 · 8 · 2 electrons
The 5s probability cloud is a hydrogen-like teaching model. It does not show collective electron bands in metallic strontium or the full electronic structure of Sr²⁺ compounds.
Strontium is represented with an ambient-pressure FCC teaching cell. Pressure-induced polymorphs are outside this introductory structure model.. 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 5s probability cloud is a hydrogen-like teaching model. It does not show collective electron bands in metallic strontium or the full electronic structure of Sr²⁺ compounds.
Where do I meet strontium?
Clickable learning cards connect the element to materials, environment, technology, biology or research - depending on what the evidence actually supports.
Red emission
Strontium salts are valued for strong red color in pyrotechnic and signal compositions.
Sr atom → Sr²⁺ → red emission → isotope tracer
Strontium connects simple Group 2 chemistry with spectroscopy and geochemistry.
5s² neutral atom
Two outer electrons set up Group 2 chemistry.
Calcium, strontium and barium
Compare nearby elements to see which patterns repeat and which properties remain element-specific.
| Atomic no. | 20 |
|---|---|
| Outer shell | 4s² |
| Atomic no. | 38 |
|---|---|
| Outer shell | 5s² |
| Atomic no. | 56 |
|---|---|
| Outer shell | 6s² |
Strontium 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 | 38 | Source-reviewed; see Sources below | Evaluated |
| Relative atomic mass | 87.62 | Source-reviewed; see Sources below | Evaluated |
| Ground-state electron configuration | [Kr] 5s² | Source-reviewed; see Sources below | Evaluated |
| Group / period / block | Group 2 · Period 5 · s-block | Periodic-table placement | Evaluated |
| Electronegativity | 0.95 | Source-reviewed; see Sources below | Evaluated |
| Reference isotope | ⁸⁸Sr | Source-reviewed; see Sources below | Evaluated |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| State context | Soft silvery solid at 20 °C | Source-reviewed; see Sources below | Evaluated |
| Density | 2.64 g/cm³ | Source-reviewed; see Sources below | Evaluated |
| Material / molecular structure | Strontium metal · face-centred cubic | Strontium is represented with an ambient-pressure FCC teaching cell. Pressure-induced polymorphs are outside this introductory structure model. | Measured |
| Classification | Alkaline earth metal | Periodic-table / chemistry classification | Evaluated |
| Structure-model scope | Strontium is represented with an ambient-pressure FCC teaching cell. Pressure-induced polymorphs are outside this introductory structure model. | Teaching visualization; exact crystallographic coordinates are not implied unless stated. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Melting / transition reference | 1050 K | Source-reviewed; see Sources below | Evaluated |
| Boiling / gas reference | 1650 K | Source-reviewed; see Sources below | Evaluated |
| Phase-path context | At approximately standard pressure, strontium is solid below about 1050 K, liquid to about 1650 K, and gaseous above that reference. High-pressure solid transitions are not placed on this ordinary-pressure teaching track. | 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 |
|---|---|---|---|
| Ordinary electrical behavior | Metallic conductor | Qualitative bulk behavior; exact resistivity depends on temperature, purity and alloy state. | Measured |
| Conduction model | Collective solid-state electrons | Do not interpret isolated-atom orbital clouds as literal current paths. | Reviewed |
| Surface / compound caveat | Oxides, salts and alloys can behave differently from the pure metal | Material context | Reviewed |
| Engineering values | Condition-dependent | Use condition-specific materials data for engineering calculations. | Reviewed |
| Property | Value | Context / provenance | Evidence |
|---|---|---|---|
| Common oxidation states | +2 | Source-reviewed; see Sources below | Evaluated |
| Ion / common ion context | Sr²⁺ | Source-reviewed; see Sources below | Evaluated |
| Periodic chemistry context | Strontium is the Period 5 member of Group 2, below calcium and above barium. Its two outer 5s electrons underpin common +2 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 |
|---|---|---|---|
| ⁸⁸Sr | Stable · most abundant natural isotope | The reference nucleus contains 38 protons and 50 neutrons. | Evaluated |
| ⁸⁶Sr and ⁸⁴Sr | Stable natural isotopes | Both contribute to the natural isotope mixture. | Evaluated |
| ⁸⁷Sr | Stable with radiogenic contribution | ⁸⁷Sr is stable but can be produced by long-lived ⁸⁷Rb decay, making isotope ratios geologically informative. | Evaluated |
| Teaching nucleus | ⁸⁸Sr · 38 protons + 50 neutrons | Reference isotope used in the nucleus model | Reviewed |
Is Strontium a solid, liquid or gas? State at temperature
At approximately standard pressure, strontium is solid below about 1050 K, liquid to about 1650 K, and gaseous above that reference. High-pressure solid transitions are not placed on this ordinary-pressure teaching track.
Where on Earth is Strontium found or produced?
Who discovered Strontium, and when?
Adair Crawford recognized that a mineral from Strontian, Scotland differed from known barium minerals.
Humphry Davy isolated strontium by electrochemical methods.
Strontium compounds became important in red pyrotechnics, ferrite magnets and specialized glass.
Stable and radiogenic strontium isotopes are widely used as tracers in Earth and environmental sciences.
From celestite to strontium materials: a high-level path
Strontium commonly occurs in minerals such as celestite rather than as native metal.
Mining and mineral processing concentrate strontium-bearing material.
Industrial conversion produces compounds tailored for magnets, glass, ceramics and other uses; operational recipes are outside this guide.
Applications and analytical isotope work use different chemical forms and should not be conflated with elemental strontium metal.
What is strontium used for?
Pyrotechnic red color
Strontium compounds are used to create intense red emission.
Ferrite magnets
Strontium ferrite is a widely used permanent-magnet material.
Isotope geochemistry
Strontium isotope ratios trace geological and environmental processes.
Glass & ceramics
Strontium compounds are used in selected specialty glass, ceramic and electronic materials.
Strontium isotopes and natural abundance
⁸⁸Sr
Stable · most abundant natural isotopeThe reference nucleus contains 38 protons and 50 neutrons.
⁸⁶Sr and ⁸⁴Sr
Stable natural isotopesBoth contribute to the natural isotope mixture.
⁸⁷Sr
Stable with radiogenic contribution⁸⁷Sr is stable but can be produced by long-lived ⁸⁷Rb decay, making isotope ratios geologically informative.
Five-question Strontium check
Atomic number of strontium?
Typical ion?
Common pyrotechnic color?
Important ore mineral?
Why is ⁸⁷Sr geochemically useful?
Strontium 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 strontium’s atomic number?
Short answer: 38.
Atomic number is defined by proton count, so 38 protons are what make an atom strontium. A neutral strontium atom also has 38 electrons, while isotopes can have different neutron counts without changing the element.
Key point: Atomic number = proton count.
Is strontium a metal?
Short answer: Yes. It is an alkaline-earth metal in Group 2.
This guide classifies Strontium as an alkaline earth metal. Its periodic position is Period 5, s-block, Group 2. Strontium is the Period 5 member of Group 2, below calcium and above barium. Its two outer 5s electrons underpin common +2 chemistry.
Key point: Periodic-table classification describes recurring atomic/chemical behavior; it does not make every element in a column physically identical.
How many valence electrons does strontium have?
Short answer: Two, because its neutral ground-state configuration ends in 5s².
The neutral-atom ground-state reference used on this page is [Kr] 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 +2, 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.
Why are strontium compounds used for red color?
Short answer: Excited strontium species can emit strongly in red wavelengths, which is why strontium salts are common colorants in pyrotechnics.
Pyrotechnic red color: Strontium compounds are used to create intense red emission. Ferrite magnets: Strontium ferrite is a widely used permanent-magnet material. Elemental strontium, Sr²⁺ in salts, red-emitting strontium compounds and strontium isotope ratios are related but distinct scientific contexts.
Key point: Always distinguish the pure element from the compound, alloy, isotope or device material that actually performs the application.
What mineral is an important source of strontium?
Short answer: Celestite, SrSO₄, is a major strontium mineral commodity.
Celestite supply Celestite (SrSO₄) is an important strontium mineral commodity. Neutral strontium ends in 5s² and commonly forms Sr²⁺.
Key point: Use the direct answer together with the material, isotope and evidence context shown elsewhere on the page.
Why is ⁸⁷Sr important in geology?
Short answer: ⁸⁷Sr can be produced by ⁸⁷Rb decay, so isotope ratios can record source and age-related geological information.
⁸⁷Sr can include radiogenic contribution from ⁸⁷Rb decay, making isotope ratios useful in geology. ⁸⁷Sr Stable with radiogenic contribution ⁸⁷Sr is stable but can be produced by long-lived ⁸⁷Rb decay, making isotope ratios geologically informative.
Key point: The mechanism matters: connect the observed behavior to electron structure, bonding, phase or the specific material form rather than memorizing the result alone.
Scientific sources for Strontium
- Royal Society of Chemistry - Strontium
- NIST - Atomic Data for Strontium
- USGS - Mineral Commodity Summaries 2026
Questions to ask next about Strontium
A good element lesson should lead to the next useful question, not end after a list of facts.
Found an error, something unclear, or a missing topic?
Tell us what you noticed. Feedback goes to a private review queue and is never published automatically.