group 2 Flashcards
What is formed when group 2 elements react with
oxygen?
Group 2 metal oxide
This is a redox reaction
What is observed when group 2 elements react with
oxygen?
● Beryllium only reacts in powdered form.
● Magnesium burns with an intense white flame.
● Calcium burns with a bright white flame (red at the
top).
● Strontium is reluctant to start burning but burns
intensely with a white flame.
● Barium burns with a white flame.
Write an equation for the reaction between calcium
and oxygen
Ca(s) + ½O2(g) → CaO(s)
How do group 2 elements react with water?
An alkaline hydroxide and hydrogen gas
This is a redox reaction
Describe the trend in the reactions with water as you
go down group 2
As you go down the group, the reactions
become more vigorous.
Write an equation for the reaction between strontium
and water
Sr + 2H2O → Sr(OH)2 + H2
Why does beryllium only react with steam at very
high temperatures and not with cold water?
Because beryllium is the least reactive
group 2 metal.
Why does magnesium stop reacting with cold water
after a short time?
Because an insoluble coat of magnesium
hydroxide forms on the surface.
What is formed when group 2 elements react with
dilute acids?
A salt and hydrogen gas
This is a redox reaction
Write an equation for the reaction between
magnesium and hydrochloric acid
Mg + 2HCl → MgCl2 + H2
Describe the trend in the reactivity of group 2 metals
with hydrochloric acid
Reactivity increases / the reactions get
more vigorous.
Describe and explain the trend in the reactivity of
group 2 metals with sulfuric acid
The reactions do not get more vigorous down the group due to the solubility of
the sulfates produced.
- Beryllium and magnesium: soluble sulfates so similar reaction as with HCl
- Calcium: sparingly soluble sulfate
- Strontium and barium: insoluble sulfates
Calcium, strontium and barium only react with sulfuric acid for a short time as
the formation of the insoluble sulfate on the metal stops the reaction.
Why might a precipitate be seen when a group 2
oxide reacts with water?
Group 2 hydroxides are only slightly soluble in water so when the solution is saturated, the metal hydroxide doesn’t dissolve (meaning it appears as a precipitate).
Write an equation for the reaction between calcium
oxide and water
CaO(s) + H2O(l) → Ca(OH)2(aq)
Describe the trend in the solubility of group 2
hydroxides. Use this to explain the trend in pH
The solubility of group 2 hydroxides
increases down the group. As a result,
more OH- ions are release in solution
meaning pH increases down the group.
Which group 2 oxide doesn’t react with water?
Beryllium oxide
What is formed when group 2 oxides react with dilute
acids?
A salt and water
Write an equation for the reaction between barium
oxide and hydrochloric acid
BaO + 2HCl → BaCl2 + H2O
How do group 2 hydroxides behave in water? Use
Ca(OH)2 as an example
Group 2 hydroxides dissociate in water
to form their constituent ions:
2+ - Ca(OH)2(s) → Ca (aq) + 2OH (aq)
What is formed when group 2 hydroxides react with
dilute acids?
A salt and water
E.g. Ca(OH)2 + 2HCl → CaCl2 + 2H2O
How do group 2 carbonates behave in water?
All group 2 carbonates are sparingly
soluble in water. They do not react with
water.
What is formed when group 2 carbonates react with
dilute acids?
A salt, water and carbon dioxide gas
Write an equation for the reaction between
magnesium carbonate and nitric acid
MgCO3 + 2HNO3 → Mg(NO3)2 + CO2 + H2O
Describe how group 2 nitrates thermally decompose
Upon heating, group 2 nitrates
decompose to form a group 2 metal
oxide, nitrogen dioxide and oxygen gas.
Write an equation for the thermal decomposition of
strontium nitrate
Sr(NO3)2 → SrO + 2NO2 + ½O2
Describe the thermal decomposition of group 2
carbonates
Upon heating, group 2 carbonates decompose to
form a group 2 oxide and carbon dioxide.
E.g. CaCO3 → CaO + CO2
What is the use of Ca(OH)2 and CaCO3 in agriculture?
● Both compounds can be added to soil to raise the pH
so that it is not too acidic to grow crops. This is
because they react with and neutralise acids.
● CaCO3 is used in the manufacture of quicklime,
slaked lime, cement and mortar.
● Ca(OH)2 is used for cement, mortar and sewage
treatment.
