Group 2 Metals

Question 1

What are group two metals also known as?

Answer 1

The alkaline earth metals.

Question 2

What bonding occurs in G2?

Answer 2

Metallic.

Question 3

Starting from Be list G2 to Ra.

Answer 3

Be, Mg, Ca, Sr, Ba, Ra.

Question 4

Trend of atomic radius down G2?

Answer 4

Increases.

Question 5

Why does atomic radius change down G2?

Answer 5

More principal energy levels are occupied. These levels are further from the nucleus and additional shells shield the outer e-s from the nuclear charge. The outer e-s are attracted less strongly the further from the nucleus they are.

Question 6

Trend of 1st ionisation energy down G2?

Answer 6

Decreases.

Question 7

Why does the 1st ionisation energy change down G2?

Answer 7

Outer e- is removed more and more easily, e- is removed from a successively higher principal energy level further from the nucleus. More shielding/ no. of energy levels between the outer shell and the nucleus. Extra inner e-s shield the outer e-s from the increased nuclear charge so less energy is needed to remove it.

Question 8

Trend of m.p and b.p down G2?

Answer 8

Decreases.

Question 9

Why does m.p and b.p change down G2?

Answer 9

All metallically bond and each atom gives 2 e-s into the structure, the attraction between the + ion and - e-s hold the metal together, the stronger the attraction the higher the m.p. The + ions get bigger down the group and the extra shells of e-s shield the attraction of the metal ion nuclei and the free e-s. Metallic bonds get easier to break and m.p is lower.

Question 10

What element is the exception to the m.p trend in G2?

Answer 10

Mg.

Question 11

Why is Mg lower m.p?

Answer 11

Has a different metallic structure.

Question 12

How does Mg react with water?

Answer 12

Reacts very slowly with cold water, readily with steam.

Question 13

Equation for Mg and water?

Answer 13

Mg(s) + H2O(g) -> MgO(s) + H2(g).

Question 14

How does Ca react with water?

Answer 14

Reacts with cold water.

Question 15

Equation for Ca and water?

Answer 15

Ca(s) + 2H2O(l) -> Ca(OH)2(aq) + H2(g).

Question 16

How does Sr react with water?

Answer 16

Reacts quickly with water.

Question 16

What is the equation for Sr and water?

Answer 16

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

Question 17

How does Ba react with water?

Answer 17

Reacts very quickly with cold water.

Question 18

Equation for Ba and water?

Answer 18

Ba(s) + 2H2O(l) -> Ba(OH)2(aq) + H2(g).

Question 19

What is the trend in reactivity with water down G2?

Answer 19

Increase in reactivity.

Question 20

Explain the trend in G2 reactivity with water.

Answer 20

Down the group the outer e-s are further from the nucleus and are lost more easily making the element more reactive. There is more shielding of the outer e-s as we go down the group.

Question 21

Define solubility.

Answer 21

Dissolves in water.

Question 22

Define insolubility.

Answer 22

Doesn’t dissolve in water.

Question 23

As we go down the group how does reactivity of hydroxides change?

Answer 23

Increases.

Question 24

As we go down the group how does reactivity of sulphates change?

Answer 24

Decreases.

Question 25

How soluble is Mg(OH)2?

Answer 25

Sparingly.

Question 26

What is magnesium hydroxide used for?

Answer 26

Laxatives, medicine for digestive upset.

Question 27

What is calcium hydroxide used for?

Answer 27

In agriculture to neutralise acidic soil.

Question 28

What is calcium oxide or calcium carbonate used for?

Answer 28

Remove sulphur dioxide from flue gases in a chimney. Line the chimney with it and it reacts with the sulphur dioxide. They are both bases, this is a neutralisation reaction.

Question 29

How soluble is BaSO4?

Answer 29

Insoluble.

Question 30

What is barium sulphate used for?

Answer 30

Barium meal is given to patients when X rays of the digestive system are needed. It can be used in medicine as it's insoluble and isn't absorbed.

Question 31

What is magnesium used for?

Answer 31

Extract titanium from titanium chloride in industry to get titanium metal. Displacement reaction, Mg is more reactive than Ti.

Question 32

Displacement equation for Mg and Ti?

Answer 32

2Mg + TiCl4 -> 2MgCl2 + Ti.

Question 33

What do we do to test for sulphate ions?

Answer 33

Add 1cm^3 of dilute HCl to solution being tested. Add 1cm^3 of dilute barium chloride to test tube.

Question 34

If sulphate ions are present what result occurs?

Answer 34

A white precipitate of barium sulphate is formed.

Question 35

Why do we add acid to the solution in the sulphate test?

Answer 35

To remove any other ions that would also give a precipitate.

Question 36

What other ions would give a precipitate if not removed by acid?

Answer 36

Carbonate ions, CO3^2-.

Question 37

Why don't we use sulphuric acid in our sulphate ions test?

Answer 37

It contains sulphate ions that would also give a white precipitate.

Question 38

How do we calc. % mass?

Answer 38

Moles of one you know, mass of other reactant, difference in masses, do percentage over whole mass of reactants.

Question 39

Write an ionic equation, with state symbols, to show the reaction of calcium with an excess of water.

Answer 39

Ca(s) + 2H2O(l) -> Ca2+(aq) + 2OH-(aq) + H2(g)

Question 40

Write an equation for the thermal decomposition of zinc carbonate to zinc oxide.

Answer 40

ZnCO3 -> ZnO + CO2

Question 41

How do you do % atom economy?

Answer 41

New comp/ old comp x 100