Some properties of the alkaline metals

Some properties of the alkaline metals

▪ Table
Some properties of the alkaline metals
beryllium magnesium calcium
atomic number 4 12 20
atomic weight (stablest isotope) 9.0122 24.312 40.08
colour of element gray silvery white silvery white
melting point (°C) 1,283 650 842–48
boiling point (°C) Some properties of the alkaline metals2,500 1,105 1,487
density at 20 °C (grams per cubic centimetre) 1.85 1.74 (5 °C) 1.54
oxidation number 2 2 2
mass number of most common isotopes (terrestrial abundance, percent) 9 (100) 24 (78.70), 25 (10.13), 26 (11.17) 40 (96.97), 42 (0.64), 43 (0.145), 44 (2.06), 46 (0.0033), 48 (0.18)
radioactive isotopes (mass numbers) 7, 10–11 20–23, 27–28 37–39, 41, 45, 47, 49, 50
electrical resistivity at 0 °C (microhm-centimetres) 4.0 4.45 3.91
crystal structure* HCP HCP FCC, HCP, BCC
radius, ionic (+2 ion, angstroms) 0.31 0.65 0.99
diameter, atomic (angstroms) (coordination number of 12) 2.25 3.20 3.93
ionization energy (electron volts)
first 9.32 7.64 6.11
second 18.21 15.03 11.87
third 153.85 80.12 51.21
electrode potential for reduction from the +2 to 0 oxidation state at 25 °C (volts) −1.85 −2.37 −2.87
electronegativity (Pauling) −1.5 −1.2 −1.0
strontium barium radium
atomic number 38 56 88
atomic weight (stablest isotope) 87.62 137.34 (226)
colour of element silvery white silvery white silvery white
melting point (°C) 769 725 700
boiling point (°C) 1,384 1,640 1,140
density at 20 °C (grams per cubic centimetre) 2.54 3.51 (about 5)
oxidation number 2 2 2
mass number of most common isotopes (terrestrial abundance, percent) 84 (0.56), 86 (9.86),87 (7.02), 88 (82.56) 130 (0.101), 132 (0.097), 134 (2.42), 135 (6.59), 136 (7.81), 137 (11.32), 138 (71.66) —
radioactive isotopes (mass numbers) 80–83, 85, 89–93, 95 123, 125–29, 131, 133, 139–43 213–17, 219–30
electrical resistivity at 0 °C (microhm-centimetres) 23 60 —
crystal structure* FCC, HCP, BCC BCC —
radius, ionic (+2 ion, angstroms) 1.13 1.35 1.40
diameter, atomic (angstroms) (coordination number of 12) 4.30 4.48 —
ionization energy (electron volts)
first 5.69 5.21 5.28
second 11.03 10.00 10.14
third — — —
electrode potential for reduction from the +2 to 0 oxidation state at 25 °C (volts) −2.89 −2.90 −2.92
electronegativity (Pauling) −1.0 −0.9 −0.9
*HCP = hexagonal close-packed, FCC = face-centred cubic (cubic close-packed), BCC = body-centred cubic.
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Universalium. 2010.

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