Group 2

Question 1

What are the group 2 metals known as?

Answer 1

The alkali metals

Question 2

What block is group 2 in?

Answer 2

S block

Question 3

What ions do group 2 form? How?

Answer 3

They lose 2 electrons to form 2+ ions when they react in order to achieve a full outer shell

Question 4

What is the electron configuration of the atom and of the ion for Be?

Answer 4

Atom: 1S²2S²
Ion: 1S²

Question 5

What is the electron configuration of the atom and of the ion for Mg?

Answer 5

Atom: 1S²2S²2P⁶3S²
Ion: 1S²2S²2P⁶

Question 6

What is the electron configuration of the atom and of the ion for Ca?

Answer 6

Atom: 1S²2S²2P⁶3S²3P⁶4S²
Ion: 1S²2S²2P⁶3S²3P⁶

Question 7

Does the atomic radius of group 2 metals increase or decrease going down the group? Why?

Answer 7

Increase down the group due to additional electron shells

Question 8

Describe the reactivity of group 2 metals going down the group?

Answer 8

Increases down the group as when group 2 react they lose 2 electrons forming 2+ ions. The easier it is to lose electrons the more reactive they are

Question 9

Describe the first ionisation energy going down group 2

Answer 9

Decreases as each element down group has an extra shell which shields the outer electrons from the positive nucleus. The extra shells mean the outer electrons are further away from the nucleus, reducing the attraction. The positive charge of the nucleus does increase down group but this is overridden by the extra shells

Question 10

Does the melting points of group 2 metals increase or decrease going down the group? Why?

Answer 10

In general they decrease but theres a blip at Mg because the crystal structure changes

Question 11

Describe the structure of group 2 metals

Answer 11

They have metallic structures with positive ions in a crystal structure surrounded by delocalised electrons from the outer shell

Question 12

What effect does the atomic radius have on the melting point of group 2 metals?

Answer 12

The bigger the radius the further away the delocalised electrons are from the positive charge so less attraction they feel. It will take less energy to break the bonds so melting point goes down

Question 13

What type of reaction is it when group 2 metals react with water?

Answer 13

Redox reaction

Question 14

What is the general equation for when group 2 metals react with water?

Answer 14

Metal + Water → Metal Hydroxide + Hydrogen

Question 15

Describe how readily the group 2 metals react when reacted with water

Answer 15

The further down the group the more readily they react
Be - Doesn’t react
Mg - Very slowly
Ca - Steadily
Sr - Quickly
Ba - Rapidly

Question 16

What do solubility trends depends on?

Answer 16

The compound ion

Question 17

Describe the solubility trends for group 2 metals

Answer 17

Generally compounds containing singly charged anions increase in solubility down the group and compounds containing doubly charged anions decrease in solubility going down the group

Question 18

Describe the solubility of group 2 hydroxides. Which element is the most soluble? Which is the least soluble?

Answer 18

Mg - Least soluble
Ca
Sr
Ba - Most soluble

Question 19

Describe the solubility of group 2 sulphates. Which element is the most soluble? Which is the least soluble?

Answer 19

Mg - Most soluble
Ca
Sr
Ba - Least soluble

Question 20

How can you test for sulphates?

Answer 20

If acidified barium chloride (BaCl2) is added to a solution containing sulphate ions then a white precipitate of barium sulphate is formed

Question 21

When testing for sulphates why does the solution need to be acidified with HCL

Answer 21

To get rid of any sulphites or carbonates which also produces a white precipitate

Question 22

How can Mg be used for the extraction of Titanium from its ore?

Answer 22

1. The main ore, Titanium (IV) oxide, TiO2 os first converted to titanium (IV) chloride, TiCl4, by heating it with carbon in a stream of chlorine gas
2. This is then purified by fractional distillation and then is reduced by Mg in a furnace at 1000•c

Question 23

What is the equation when Mg is used to extract Titanium from its ore?

Answer 23

TiCl4(g) + 2Mg(l) → Ti(s) + 2MgCl2(l)

Question 24

How and why is barium sulphate used in barium meals?

Answer 24

1. Barium Sulphate is opaque to X-rays so can be used to help diagnose problems
2. The patient swallows the suspension of barium sulphate, this coats the tissue so they show up on the X-ray, showing the structure of the organs

Question 25

Give 2 examples how group 2 metals can be used to neutralise acid

Answer 25

1. Calcium Hydroxide (slaked lime, Ca(OH)2) is used to neutralise acidic soil in farming
2. Magnesium Hydroxide (Mg(OH)2) is used in indigestion tablets as antacid

In both cases the reaction is: H+(aq) + OH-(aq) → H20(l)

Question 26

How is calcium oxide and calcium carbonate used to remove sulphur dioxide?

Answer 26

1. Burning fossil fuel produces sulphur dioxide which pollutes the atmosphere
2. Acidic SO2 can be removed from flue gases by reacting with an alkali, this is wet scrubbing
3. Powdered calcium oxide (lime) and calcium carbonate (limestone) can be used for this
4. A slurry is made, mixing the oxide or carbonate with water. This is then sprayed onto the flue gases. The sulphur dioxide reacts and produces calcium sulphite

Question 27

What is the equations for when calcium oxide and calcium carbonate is used to remove sulphur dioxide?

Answer 27

CaO(s) + 2H2O(l) + SO2(g) → CaSO3(s) + 2H2O(l)

CaCO3(s) + 2H2O(l) + SO2(g) → CaSO3(s) + 2H2O(l) + CO2(g)