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Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal , strontium is a soft silver-white yellowish metallic element that is highly chemically reactive . The metal forms a dark oxide layer when it is exposed to air.
The alkaline earth metal strontium (38 Sr) has four stable, naturally occurring isotopes: 84 Sr (0.56%), 86 Sr (9.86%), 87 Sr (7.0%) and 88 Sr (82.58%). Its standard atomic weight is 87.62(1). Only 87 Sr is radiogenic ; it is produced by decay from the radioactive alkali metal 87 Rb , which has a half-life of 4.88 × 10 10 years (i.e. more than ...
atomic mass Electronegativity (Pauling) ... Strontium: Sr: 87.62(1) ... a few atomic radii are calculated, not experimental [—] a long dash marks properties for ...
Strontium is the second element placed in the 5th period. ... Its atomic mass is 91.224. It is a lustrous, gray-white, strong transition metal that resembles titanium.
Key physical and atomic properties of the alkaline earth metals; Alkaline earth metal Standard atomic weight [n 2] [20] [21] Melting point Melting point Boiling point [4] Boiling point [4] Density (g/cm 3) [22] Electronegativity First ionization energy (kJ·mol −1) Covalent radius [23] Flame test color Beryllium: 9.012182(3) 1560: 1287: 2744
Naturally occurring strontium is nonradioactive and nontoxic at levels normally found in the environment, but 90 Sr is a radiation hazard. [4] 90 Sr undergoes β − decay with a half-life of 28.79 years and a decay energy of 0.546 MeV distributed to an electron, an antineutrino, and the yttrium isotope 90 Y, which in turn undergoes β − decay with a half-life of 64 hours and a decay energy ...
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Elements and atomic masses [2] [3] Element 1 mass Element 2 Mean of 1 and 3 Actual mass Element 3 mass Alkali-forming elements Lithium 6.941 u Sodium 22.989769 u 23.01965 u Potassium 39.0983 u Alkaline-earth-forming elements [atomic masses verification needed] Calcium 40.078 u Strontium 87.62 u 88.7025 u Barium 137.327 u Salt-forming elements ...