Groups 1, 2
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name the three physical properties of group two elements
• ionisation energy • atomic radius • reactivity
how does ionisation energy change down group two and why
• ionisation energy decreases down group two • greater atomic radius, increased shielding, easier to lose an electron
how does reactivity change down group two and why
• reactivity increases down group two • increased electron shielding and atomic radius, outer (valence) electron easier to lose, reactions can occur more easily
how does atomic radius change down group two and why
• atomic radius increases • additional electron shells
what type of reaction is a metal + water
redox reaction
metal + water ->
metal hydroxide + hydrogen
what kind of solution is a metal hydroxide
an alkaline solution
general equation for reaction of group 2 metals with water
M(s) + 2H2O(l) -> M(OH)2(aq) + H2(g)
how is a reaction with water different to one with steam
• steam produces a metal oxide and hydrogen • reaction with steam is faster because it has more energy
metal + steam ->
metal oxide (white powder) + hydrogen
general equation for reaction of group 2 metal and steam
M(s) + H2O(g) -> MO(s) + H2
metal + chlorine gas ->
metal chloride (white precipitate)
general equation for reaction of group 2 metal + chlorine gas
M(s) + Cl2(g) -> MCl2(s)
how does reactions with chlorine gas change down group two
• it becomes more vigorous down group 2 • because metals more reactive
metal + oxygen ->
metal oxide
general equation for group 2 metal + oxygen in normal conditions
2M(s) + O2(g) -> 2MO(s)
which two group two metals dont fit the general pattern of reaction with oxygen
strontium and barium
strontium/barium + oxygen ->
metal peroxide
when do strontium and barium become peroxides
when reacting with excess oxygen and heat energy
(with excess oxygen and heat energy) M(s) + O2(g) ->
MO2
which group 2 metals react
Mg-Ba
general equation for reactions of metal oxides and water
MO(s) + H2O(l) -> M(OH)2(aq)
general equation for reactions of metal oxides and dilute hydrochloric acid
MO(s) + 2HCl(aq) -> MCl2(aq) + H2O(l)
general equations for metal hydroxides in water
—————H2O(l)—————— M(OH)2(s) ——-> M(OH)2(aq)