Group 2

Question 1

What block do the group 2 elements exist in?

Answer 1

S-block

Question 2

Physical properties of Group 2 metals

Answer 2

Atomic radius increases down the group

Ionic size increases down the group

Melting points decrease down the group

Question 3

Chemical properties of Group 2 metals

Answer 3

Undergo redox reactions to form 2+ ions

Reactivity increases down the group

Ionisation energies decrease down the group

Question 4

What is the relationship in terms of atomic radi between positively charged ions and atoms?

Answer 4

Smaller atomic radius in positivity charged ions

Nuclear charge exceeds the electronic charge

Electrons are pulled closer to nucleus

Question 5

Why do melting points decrease down the group?

Answer 5

Metallic bonding gets weaker due to increased size and density

Question 6

How do the ionisation energies of group 2 compare with group 1?

Answer 6

Higher due to there being more electrons to remove in a energy level

Question 7

What is the trend, going down the group, when group 2 metals react with oxygen?

Answer 7

React with increasing vigour down the group

Question 8

Equation for the reaction of Mg with O2 including state symbols

Answer 8

2Mg(s) + O2(g) –> 2MgO(s)

Question 9

Ionic equations for the reaction of Mg with O2

Answer 9

Mg –> Mg2+ + 2e-

O + 2e- –> O2-

Question 10

Trend, going down the group, of the reaction of group 2 metals with water

Answer 10

React with increasing vigour

Question 11

Describe the reaction of Mg with cold water

Answer 11

Very slow

Question 12

Give the equation of the reaction of Mg with cold water

Answer 12

Mg(s) + 2H20(l) –> Mg(OH)2(aq) + H2(g)

Question 13

Give the equation of the reaction of Mg with steam

Answer 13

Mg(s) + H20(g) –> MgO(s) + H2(g)

Question 14

Trend, going down the group, of the reaction of group 2 metals with dilute acid

Answer 14

React with increasing vigour down the group

Question 15

What is produced when a group 2 metal reacts with an acid? Give an example

Answer 15

Salt + Hydrogen

Mg(s) + H2SO4(aq) –> MgSO4(aq) +H2(g)

Ca(s) + 2HCl(aq) –> CaCl2(aq) + H2

Question 16

Compare the reaction of group 2 metal with water and group 2 metal with dilute acid

Answer 16

Reactions more vigorous with dilute acid

Question 17

Ionic equation of Mg with acid

Answer 17

Mg(s) + 2H+(aq) –> Mg2+(aq) + H2(g)

Question 18

What type of solids do group 2 oxides form?

Answer 18

Ionic

except for beryllium which has covalent character

Question 19

Trend in solubility of group 2 hydroxides

Answer 19

Solubility increases down the group

Question 20

Give the equation for the reaction of calcium oxide with water

Answer 20

CaO(s) + H20(l) –> Ca(OH)2(s)

Question 21

What is the trend in basic strength down Group 2? Explain the trend

Answer 21

Basic strength increases due to the solubility of the hydroxides increasing

Question 22

What is the trend, going down the group, of charge density of group 2 metal ions?

Answer 22

As metal ions get larger, charge density decreases

Question 23

Use of Ca(OH)2

Answer 23

Farming:

Neutralises acidic soils

Question 24

Use of Mg(OH)2

Answer 24

Used in toothpaste and indigestion tablets as an antiacid

Question 25

What are Ca(OH)2 and Mg(OH)2 an example of?

Answer 25

Weak alkalis

Question 26

Trend in the ease of decomposition of Group 2 carbonates going down the group

Answer 26

Decomposition becomes harder as you move down the group

Question 27

Properties of Group 2 carbonates

Answer 27

Insoluble in water Undergo thermal decomposition to produce an oxide and CO2

Question 28

Give an equation showing the decomposition of a group 2 carbonate

Answer 28

MgCO3(s) --> MgO(s) + CO2(g)

Question 29

Trend in solubility of group 2 sulfates going down the group

Answer 29

Decreases

Question 30

What is the appearance of group 2 sulfates?

Answer 30

White, crystalline solids

Question 31

Why does solubility of group 2 sulfates decrease down the group?

Answer 31

Little change in lattice energy Cation gets larger so hydration enthalpy gets smaller A larger cation has a lower charge density so is less attracted to water molecules

Question 32

Describe the test for sulfates

Answer 32

Add dilute HCl to a sample of group 2 sulfate Add a few drops of barium chloride solution White precipitate of barium sulfate will appear if it is a sulfate

Question 33

Why is acid added in the test for sulfates?

Answer 33

To prevent precipitation of other insoluble ions such as carbonate

Question 34

Describe the appearance of the group 2 metals

Answer 34

Bright, silvery solids

Question 35

Why do group 2 metals sometimes appear dull?

Answer 35

- A slow reaction happens between the metal and oxygen in the air - This forms a surface coating of oxide which gives the dull colour - It also prevents further reaction

Question 36

Give the equation for the reaction between calcium and oxygen

Answer 36

2Ca(s) + O2(g) --> 2CaO(s)

Question 37

Give the equation for the reaction of barium with chlorine

Answer 37

Ba(s) + Cl2(g) --> BaCl2(s)

Question 38

How does milk of magnesia work? Give the equation

Answer 38

- Contains a saturated solution of magnesium hydroxide with extra solid magnesium hydroxide - This acts as an antiacid that neutralises excess stomach acid Mg(OH)2 + 2HCl --> MgCl2 + 2H2O

Question 39

Why do the hydroxide ions in milk of magnesia pose no risk to health?

Answer 39

-Low solubility of magnesium hydroxide means the concentration of OH- ions is very low

Question 40

Give the equation for the reaction between calcium oxide and nitric acid What type of reaction is it? What observations can you make?

Answer 40

CaO + 2HNO3 --> Ca(NO3)2 + H2O Neutralisation reaction White solid goes to colourless solution

Question 41

Give the equation for the reaction of calcium hydroxide with nitric acid

Answer 41

Ca(OH)2 + 2HNO3 --> Ca(NO3)2 + 2H2O

Question 42

What are basic oxides?

Answer 42

Oxides of metals that react with water to form metal hydroxides and with acids to form salts and water

Question 43

Give the equation in which limewater becomes cloudy

Answer 43

CO2(g) + Ca(OH)2(aq) --> CaCO3(s) + H20(l)