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.