Topic 4 - Inorganic Chemistry

Question 1

What is the trend in atomic radius down group 2?

Answer 1

Atomic radius increases down group 2, as the atoms have more shells of electrons, making them larger

Question 2

What is the trend in melting point down group 2?

Answer 2

Melting point decreases down group 2:
- As the metallic bonding weakens as the atomic size increases
- Due to delocalised electrons and positive ions being further apart
- So electrostatic force between delocalised electrons and positive ions weakens

Question 3

What is the trend in 1st ionisation energy down group 2?

Answer 3

1st ionisation energy decreases:
- Outermost electrons are held more weakly as they are further from the nucleus in additional shells
- Outer shell electrons are shielded from the attraction of the nucleus by the repulsive force of inner shell electrons

Question 4

What is the trend in the reactivity down group 2?

Answer 4

Reactivity increases down group 2 as:
- Atomic radii increases so increase in shielding
- Nuclear attraction decreases and its easier to remove the outer electron and form cations

Question 5

What is the reaction of group 2 with oxygen?

Answer 5

2X + O2 -> 2XO

Question 6

What is the reaction of group 2 with Chlorine?

Answer 6

X + Cl2 -> XCL2

Question 7

What is the reaction of Mg with gaseous water?

Answer 7

Mg + H2O -> MgO + H2

• Burns with bright white flame

Question 8

What is the reaction of Mg with warm water?

Answer 8

Mg + H2O -> Mg(OH)2 + H2

No flame observed

Question 9

What is the general formula for the reaction of group 2 metals with cold water?

Answer 9

X + H20 -> X(OH)2 + H2

Question 10

What are the observations for the reactions of group 2 metals with cold water?

Answer 10

• Fizzing (more vigorous down the group)
• Metal dissolves (faster down the group)
• Solution heating up (more down the group)
• With Calcium, a white precipitate forms (less precipitate down the group)

Question 11

What is the general formula for the reaction between group 2 oxides and water?

Answer 11

XO + H2O -> X(OH)2

Question 12

What is the trend in the solubility of group 2 hydroxides?

Answer 12

Group 2 hydroxides become more soluble down the group

Question 13

What is the trend in the solubility of group 2 sulfates?

Answer 13

Group 2 sulfates become less soluble down the group

Question 14

What is the general formula for the decomposition of group 2 carbonates

Answer 14

XCO3 -> XO + CO2

Question 15

What is the trend of thermal stability of group 2 carbonates down group 2?

Answer 15

Group 2 carbonates become more thermically stable:
- As the cations bigger they have less of a polarising effect and distort the carbonate ion less. The C-O bond is weakened less so it less easily breaks down

Question 16

What is the trend in the thermal stability of group 1 carbonates

Answer 16

Group 1 carbonates do not decompose with the exception of Lithium:
- As they only have +1 charges, which isn’t enough to polarise the carbonate ion

Question 17

What is the general formula for the decomposition of group 2 nitrates?

Answer 17

2X(NO3)2 -> 2XO + 4NO2 + O2

Question 18

How do we test for the presence of carbonate ions?

Answer 18

• Add any dilute acid and observe effervesence
• Bubble gas through limewater to test for CO2 - Will turn cloudy
• Fizzing due to presence of CO2