Alkaline Earths

Metals (ns2) - easily oxidized to M2+

- less reactive than alkalis of same period

reactivity: Be < Mg < Ca < Sr < Ba

WHY? -

• Size INCREASES as ? group

• VALENCE e- are farther from nucleus

• same Z* - Valence e- less tightly held

• Therefore valence e- are easier to remove

Typical reactions / compounds

Oxides: M +1/2O2 (g) ? MO (s) CaO (lime) - #5 Ind. Chem

Halides: M + X2 (g) ? MX

Carbonates: CaCO3 (limestone) ? CaO + CO2

RECALL: Solubility rules and PRECIPITATION REACTIONS

Sulfates:

CaSO4.2H2O (gypsum) ? CaSO4. 0.5H2O (plaster-of-paris) + 3/2H2O

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