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Flashcards in Group 2 Deck (9)
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Physical properties of Group 2

Alkaline earth metal
Metal hydroxide formed
Reactive, only found in stable compounds


Reducing agent

Group 2 reduces other species
Reducing agent get oxidised


Redox reaction with oxygen

Forms metal oxide
2Mg(s) + O2(g) =>2MgO(s)


Redox reaction with water

Form alkaline hydroxide
Reaction becomes more vigorous with metals further down group
Not all hydrogen reduced

Sr(s) + 2H2O(l) => Sr(OH)2(aq) +H2(g)


Redox reaction with dilute acid

Form salt and hydrogen gas
Reaction becomes more vigorous down group

Mg(s) + 2HCl(aq) => MgCl2(aq) + H2(g)


Trends in reactivity and ionisation energy

Reactivity increases down group
React by losing electrons, form 1+ ions
Ionisation energies decrease down group, increased atomic radius, increased shielding, easier to lose e-


Reactions with water, group 2 oxides

Release OH-, form alkaline metal hydroxide solution
Slightly soluble in water
When solution saturated, metal and hydroxide in excess form solid precipitate of metal hydroxide

CaO(s) + H2O(l) => Ca2+(aq) + 2OH-(aq)


Solubility of hydroxides

Increases down group, more alkaline solutions, pH increases
Can test this in experiment


Use as bases

Used to neutralise acids
Ca(OH)2- increase pH of acidic soil, forming neutral water
Mg(OH)2, CaCO3- neutralise stomach acid, form water