4A:Elements of Group 1 and 2

Question 1

Give some properties of group 1 metals

Answer 1

Less dense than water
Low melting points
Soft

Question 2

How does ionisation energy change going down group 2 and why?

Answer 2

Decreases
Every element has an extra electron shell
More shielding occurs, distance from the nucleus increases, and effective nuclear charge doesn’t change

Question 3

How does melting temperature change going down group 2 and why?

Answer 3

Decreases

Charge density decreases as you do down the group so less energy needed to overcome electrostatic attraction

Question 4

How does atomic and ionic radii change going down group 1 & 2 and why?

Answer 4

Increases

Number of orbitals increases going down the group

Question 5

What is the first ionisation energy of group 2 metals in comparison to group 1 metals?

Answer 5

Group 2 metals have larger first ionisation energy

As they have an increased nuclear charge but decreased radii

Question 6

What is the melting points of group 2 metals in comparison to group 1 metals?

Answer 6

Higher melting points

As they lose 2 electrons per atom for metallic bonding therefore it is stronger

Question 7

What is the electrical conductivity of group 2 metals in comparison to group 1 metals?

Answer 7

Better electrical conductivity

Question 8

What is the hardness of group 2 metals in comparison to group 1 metals?

Answer 8

Harder than group 1 metals

Question 9

What is the oxidation number of group 1 and 2 ions?

Answer 9

+1 : Group 1

+2 : Group 2

Question 10

What are group 1 and 2 metals usually in redox reactions?

Answer 10

Reducing agents

Question 11

What happens when group 2 metals react with water?

Answer 11

Metal hydroxides (aq) and hydrogen are formed
M + 2H2O -> M(OH)2 + H2

Question 12

How does the reactivity of the group 1 and 2 metals change as you go down?

Answer 12

They get more reactive (outer electron more easily lost)

Question 13

What happens when group 2 metals react with oxygen?

Answer 13

Burn brightly in air (except beryllium) to form white solids

2M + O2 -> 2MO

Question 14

What happens when group 2 metals react with chlorine?

Answer 14

Solid white chlorides form (except beryllium which forms a covalent anhydrous chloride)
M + Cl2 -> MCl2

Question 15

How reactive are group 2 metals in relation to group 1?

Answer 15

Less reactive as group 1 only need to lose 1 electron

Question 16

Why must Mg and Ca be reacted with steam in order to form their metal oxides?

Answer 16

They are not as reactive as the other group 2 metals

In cold water they form their metal hydroxides instead

Question 17

What are the oxides and hydroxides of group 2?

Answer 17

Bases (will react with water to form OH- ions

Question 18

What is the exception to the group 2 oxide bases?

Answer 18

Beryllium oxide - doesn’t react with water & hydroxide is insoluble
Magnesium oxide - reacts slowly & hydroxide isn’t very soluble

Question 19

How does the strength of the base change going down group 2?

Answer 19

Increases as they become more soluble

Question 20

As group 2 metal oxides/hydroxides are bases what can they do?

Answer 20

Neutralise dilute acids to form corresponding salts

Question 21

What is produced when calcium oxide reacts with water?

Answer 21

Reacts quickly to form Ca(OH)2

Limewater

Question 22

What does amphoteric mean?

Answer 22

A chemical which can react as both an acid or an alkali

Question 23

How does the solubility of group 2 hydroxides change going down the group?

Answer 23

Becomes more soluble

Question 24

How does the solubility of group 2 sulphates change going down the group?

Answer 24

Decreases in solubility

Question 25

What is a barium meal?

Answer 25

Used in medicine as very insoluble (barium sulphate) to highlight areas of the body

Question 26

What happens when group 2 oxides react with hydrochloric acid?

Answer 26

MO + 2HCl -> MCl2 (aq) + H2O

Question 27

What happens when group 2 hydroxides react with hydrochloric acid?

Answer 27

M(OH)2 (aq/s) + 2HCl -> MCl2 (aq) + 2H20

Question 28

What happens when group 2 hydroxides react with sulphuric acid?

Answer 28

M(OH)2 (aq/s) + H2SO4 -> MSO4 (aq/s) + 2H20

Question 29

What is thermal decomposition?

Answer 29

When a substance breaks down when heated

Question 30

What does a thermally stable compound do?

Answer 30

Requires more heat to break it down

Question 31

How can anions be made unstable?

Answer 31

By the presence of a cation | This distorts the anion

Question 32

What is the affect of the distortion of anions?

Answer 32

Greater the distortion the less stable the compound

Question 33

How does the size of the cation affect the distortion?

Answer 33

The larger the cation, the less the distortion | As lower charge density

Question 34

Why do elements in group 1 & 2 become more thermally stable going down the group?

Answer 34

Charge density decreases going down group Causes less distortion of the anion Therefore more stable

Question 35

What is the thermal stability of group 1 in comparison to group 2 metals?

Answer 35

Group 1 compounds are more thermally stable | As greater charge of group 2 metals cause more distortion

Question 36

What is the thermal stability of group 1 carbonates?

Answer 36

``` Thermally stable (except lithium carbonate) ```

Question 37

What is the thermal stability of group 2 carbonates?

Answer 37

Decomposes easily | MCO3 (s) -> MO (s) + CO2

Question 38

What is the thermal stability of group 1 nitrates?

Answer 38

Decomposes easily (Except lithium) 2MNO3 (s) -> 2MNO2 (s) + O2

Question 39

What is the thermal stability of group 2 nitrates?

Answer 39

Decompose easily | 2M(NO3)2 (s) -> MO (s) + 4NO2 + O2

Question 40

How can you test the thermal stability of nitrates?

Answer 40

How long it takes to produce a certain amount of oxygen | How long until a certain amount of NO2 is produced

Question 41

How can you test the thermal stability of carbonates?

Answer 41

How long it takes for a certain amount of carbon dioxide to be produced

Question 42

How does the thermal decomposition change going down group 1 and 2?

Answer 42

Thermal stability increases going down the group

Question 43

How does the ion size change the polarizing affect?

Answer 43

Smaller cations have a greater polarizing affect | Causing it to decompose more readily

Question 44

What are the flame colours of group 1 metals?

Answer 44

``` Li - Red Na - Orange/yellow K - lilac Rb - red Cs - blue ```

Question 45

What are the flame colours of group 2 metals?

Answer 45

Ca - brick-red Sr - crimson Ba - green

Question 46

How would you perform a flame test?

Answer 46

Mix compound with a few drops of hydrochloric acid Heat a piece of platinum in a bunsen flame to clean it Dip wire into mixture and hold it in the flame