Periodic Table/Strontium
← RbY →
38Sr87.6200 Da

Strontium

Alkaline Earth Metal·Period 5, Group 2·s-block

Soft yellowish metallic element, belongs to group 2 of the periodic table. Highly reactive chemically. Sr-90 is present in radioactive fallout and has a half-life of 28 years. Discovered in 1798 by Klaproth and Hope, isolated in 1808 by Humphry Davy.

Gallery

Strontium Pieces under Paraffin Oil.

Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/strontium.php

Bohr model of Strontium

Physical Propertiesmass · density · phase · crystal

Atomic Mass

87.6200Da

Density

2.6400g/cm³

Phase (STP)

Solid

Melting Point

1050.2K

Boiling Point

1650.2K

Molar Heat

0.3060J/(mol·K)

Crystal Structure

FCC

Lattice Constant

6.080Å

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

200.00pm

Covalent

185.00pm

Van der Waals

249.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Kr] 5s2

Electron Shells

2, 8, 18, 8, 2

Electronegativity

0.95Pauling

Electron Affinity

0.0kJ/mol

1st Ionization Energy

5.7kJ/mol

Oxidation States

+2

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑↓
↑↓
↑↓
3d10
↑↓
4s2
↑↓
↑↓
↑↓
4p6
↑↓
5s2

Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2Short: [Kr] 5s2

Ionization Energies (38 known)

1st5.7 kJ/mol2nd11.0 kJ/mol3rd42.9 kJ/mol4th56.3 kJ/mol5th70.7 kJ/mol6th88.0 kJ/mol7th104.0 kJ/mol8th121.2 kJ/mol9th158.3 kJ/mol10th177.3 kJ/mol11th324.1 kJ/mol12th362.0 kJ/mol13th408.0 kJ/mol14th454.0 kJ/mol15th499.0 kJ/mol16th562.0 kJ/mol17th612.0 kJ/mol18th665.0 kJ/mol19th722.0 kJ/mol20th774.0 kJ/mol21th932.0 kJ/mol22th982.1 kJ/mol23th1038.0 kJ/mol24th1105.0 kJ/mol25th1165.0 kJ/mol26th1211.0 kJ/mol27th1333.4 kJ/mol28th1387.2 kJ/mol29th3344.7 kJ/mol30th3497.0 kJ/mol31th3664.0 kJ/mol32th3830.0 kJ/mol33th4053.0 kJ/mol34th4232.0 kJ/mol35th4465.0 kJ/mol36th4612.4 kJ/mol37th19345.6 kJ/mol38th20025.3 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

461
408
422
689
Sr emission
380nm750nm
460.7 nm(100%)407.8 nm(70%)421.6 nm(50%)689.3 nm(20%)

Abundanceby mass

🌍Earth's Crust
370.0 ppm
🌊Ocean
8.1 ppb
✨Universe
40.0 ppb
🧬Human Body
4.6 ppm

Log scale · ppm = parts per million by mass

Biological Role

Beneficial

Strontium ranelate used to treat osteoporosis. Incorporated into bone like calcium.

Discovery

Discovered By

A. Crawford

Named By

—

Year

1790

Nuclear Data

Known Isotopes

35

Stable Isotopes

4

Stable Mass Numbers

84, 86, 87, 88

Natural isotopic abundance (IUPAC recommended values)

Isotopes of Sr35 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
73Sr383572.96570025.3 msβ⁺ (1%), β⁺p (0.63%)5/2-—
74Sr383673.95617027.6 msβ⁺ (1%), β⁺p0+—
75Sr383774.94995385.2 msβ⁺ (1%), β⁺p (0.052000000000000005%)3/2-—
84Srstable384683.913419Stable2β⁺0+56.0000%
86Srstable384885.909261Stablestable (1%)0+986.0000%
87Srstable384986.908877Stablestable (1%)9/2+700.0000%
88Srstable385087.905612Stablestable (1%)0+8258.0000%
105Sr3867104.95900139.0 msβ⁻ (1%), β⁻n, 2n5/2+—
106Sr3868105.96317721.0 msβ⁻ (1%), β⁻n, 2n0+—
107Sr3869106.969672Unknownβ⁻, β⁻n, 2n1/2+—

Click any isotope for its full page with decay chain:

73Sr74Sr75Sr76Sr77Sr78Sr79Sr80Sr81Sr82Sr83Sr84Sr85Sr86Sr87Sr88Sr89Sr90Sr91Sr92Sr93Sr94Sr95Sr96Sr97Sr98Sr99Sr100Sr101Sr102Sr103Sr104Sr105Sr106Sr107Sr
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