Strontium compounds make the bright red light associated with some fireworks and flares. Strontium aluminate is used in materials that glow after illumination. These two examples invite comparison between light emitted during a flame and light released gradually after a material has absorbed energy.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
Why can a strontium-aluminate phosphor continue emitting after the illuminating light is removed?
Strontium aluminate phosphor formulations
FOLLOW THIS RELATIONSHIP
Absorb an earlier optical input
A doped strontium-aluminate phosphor receives light energy, with the host crystal, emitting dopants, and defects contributing to its possible persistent-luminescence behavior.
Explore the model (optional)
SrFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Optional: check your understanding
USE THE EXPLANATION
What distinguishes afterglow from reflection?
Atomic identity, reference properties and structure models
INTERACTIVE 3D38 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Kr] 5s2. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
An unusual from Strontian in Scotland prompted investigations that distinguished strontium compounds from other alkaline-earth materials. Crawford and Hope contributed to the recognition, with Hope examining the material further in 1791. Preparing the metal was a later achievement, reached by Davy in 1808. The history connects a place name, comparative mineral chemistry, and the expanding use of electricity to isolate reactive elements.
1791
Compound identity investigated
Hope's examination helped distinguish strontium from related alkaline-earth materials.
1808
Metal isolated
Davy obtained strontium through electrochemical preparation.
Strontium occurs chiefly in minerals such as celestite and strontianite. These contain the element in compounds rather than as reactive free metal. Natural strontium includes several stable , which should be distinguished from radioactive strontium-90 produced through nuclear processes; the name of the element alone does not specify the isotope.
Strontium is a soft, silvery metal whose exposed surface reacts readily, and it reacts strongly with water. Its salts can produce a crimson flame color through excitation. This familiar optical effect belongs to strontium-containing material in a particular energetic environment, rather than to the ordinary appearance of the metal.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
1050 K
at standard pressure unless noted
Boiling point in K
1655 K
101.325 kPa
Density in g/cm³
2.64 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
0.95 Pauling
Pauling scale
First ionization energy in kJ/mol
549.5 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
195 pm
single-bond covalent radius
Common oxidation states
+2
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
370 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1795 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 5
Sr 0.95 Pauling · Strontium
Electronegativity across period 5. Exact values.
Rb
0.82
Sr
0.95
Y
1.22
Zr
1.33
Nb
1.6
Mo
2.16
Tc
1.9
Ru
2.2
Rh
2.28
Pd
2.2
Ag
1.93
Cd
1.69
In
1.78
Sn
1.96
Sb
2.05
Te
2.1
I
2.66
Xe
2.6
Electronegativity down group 2
Sr 0.95 Pauling · Strontium
Electronegativity down group 2. Exact values.
Be
1.57
Mg
1.31
Ca
1
Sr
0.95
Ba
0.89
Ra
0.9
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
