3.2.2 Group 2

Question 1

Trend in atomic radius

Answer 1

Atomic radius increases

Question 2

Trend in first ionisation energy

Answer 2

Decrease down the group as extra shells are added.

Question 3

Trend in melting point

Answer 3

Generally decrease, successive shells of electrons shield the metal ion nucleus from the delocalised electrons. The melting point of magnesium is much lower than expected due to the way the metal ions pack together.

Question 4

Titanium extraction - overall method

Answer 4

Titanium is extracted from its ore rutile, TiO2. It is first converted into titanium chloride, which is then reduced to titanium using either magnesium or sodium.

Question 5

First step of titanium extraction - method

Answer 5

Titanium oxide is converted into titanium chloride, TiCl4.

Question 6

First step of titanium extraction - conditions

Answer 6

Titanium is combined with carbon and chlorine gas is passed over at a temperature of 1000’C

Question 7

First step of titanium extraction - equation

Answer 7

TiO2(s) + 2Cl(g) + 2C(s) ⟶ TiCl4(g) + 2CO(g)

Question 8

Second step of titanium extraction - method

Answer 8

Titanium chloride is reacted with magnesium to make titanium and magnesium chloride

Question 9

Second step of titanium extraction - conditions

Answer 9

Inert environment of either helium or argon gas, temperature of about 1200’C

Question 10

Second step of titanium extraction - equation

Answer 10

TiCl4(g) + 2Mg(l) ⟶ Ti + 2MgCl2(l)

Question 11

Reaction of group 2 with water

Answer 11

Group 2 reacts with water to make a hydroxide and hydrogen gas.

Question 12

Trend in group 2s reactivity with water

Answer 12

The reactivity of group 2 with water increases down the group as the ionisation energy decreases so the metals become easier to oxidise

Question 13

Magnesiums reaction with water

Answer 13

Magnesium reacts very slowly with cold water. Hot water increases the rate of reaction.

Question 14

Magnesium and steam

Answer 14

If steam is passed over heated magnesium an exothermic reaction occurs and the magnesium hydroxide decomposes into magnesium oxide and hydrogen gas.

Question 15

As you go down group 2 the solubility of the hydroxides…

Answer 15

…increases

Question 16

Uses of magnesium hydroxide

Answer 16

Used in medicine for digestive upsets and as a laxative, it is known as milk of magnesia. It reacts with hydrochloric acid and neutralises it.

Question 17

Use of calcium hydroxide

Answer 17

Known as slaked lime. Used in agriculture to neutralise soil acidity.

Question 18

As you go down group 2 the solubility of group 2 sulfates…

Answer 18

….decrease

Question 19

Calcium oxide use

Answer 19

Used in pollution control devices as it reacts with SO2 from flue gases

Question 20

Use of barium sulfate

Answer 20

Because it is so insoluble the body doesn’t absorb it so it is given to patients before x-rays as it causes their soft tissue to show up.

Question 21

Sulfate test

Answer 21

Because barium sulfate is insoluble barium can be used to test for sulfate ions. When barium ions are combined with sulfate ions a white precipitate forms. Barium chloride is usually used to provide the barium ions. Dilute hydrochloric acid or nitric acid is also added to get rid of any carbonate ions.