March Assessment

Question 1

Going across the period from sodium to argon, elements show an increasing trend in..

Answer 1

• first ionisation energies
• melting points
• atomic radii

Question 2

what is the structure and bonding of aluminium?

Answer 2

giant
metallic

Question 3

colour of bromine in cyclohexane

Answer 3

orange

Question 4

colour of iodine in cyclohexane

Answer 4

purple

Question 5

explain why halogens are non-polar

Answer 5

• Bonds are non-polar
• the atoms have same electro-negativities
• electrons are shared evenly

Question 6

how to distinguish between AgBr(s) and AgI(s)

Answer 6

aqueous reagent: Concentrated ammonia

observation in AgBr: precipitate dissolves

observation in AgI:
yellow precipitate remains

Question 7

how to distinguish between Sodium nitrate and sodium sulfate

Answer 7

aqueous reagent: Aqueous barium chloride

observation in sodium nitrate: no change

observation in sodium sulfate: white precipitate forms

Question 8

why are the melting points of Na,Mg,Al,Si higher than those of P and S

Answer 8

• Na, Mg, Al, Si are giant structures whereas P and S are simple molecular structures
• in giant structures, strong bonds need to be broken which requires lots of energy whereas in simple molecular structures, weak IMFs are broken with little energy

Question 9

why does magnesium have a high melting temperature than sodium

Answer 9

• Mg has more delocalised electrons
• the Mg cations (2+) have a greater charge than sodium ions (1+)
• Mg has a stronger attraction between cations and delocalised electrons

Question 10

suggest a reason why the enthalpy change of this reaction cannot be measured directly

Answer 10

other products will be made

Question 11

what property of electrons is represented by the arrows: electrons in boxes

Answer 11

direction of spin