Sec 3E Science Chemistry CA 2 Test 1 2014: Suggested Marking Scheme

Chemical Bonding

Section A [5%]:

MCQ1 B

MCQ2 D

X (metal) + Y (non-metal) = ionic bonding 2.8.2 2.8.7

Formula XY2

MCQ3 B MCQ4 D MCQ5 C

Section B [20%]: 6

(a) When solid, the ions are held in a fixed position [1] They cannot move freely to conduct electricity [1]

2

(b) Large amount of energy is needed to overcome the strong electrostatic forces of attraction [1] between the ions [1]

2

(c) It is soluble[1] 1

[1] Correct drawing of Na & Cl [1] [1] Correct charges and number of electron transferred [1]

2

Total 7 7

(a) Neon has a full octet electronic structure [1] Nitrogen needs to share 3 valence electrons with another nitrogen atom to attain a full octet electronic structure [1]

2

(b) Little energy is taken in to overcome the weak intermolecular forces [1] between the nitrogen molecules [1]

2

Total 4 8

(a) Q: 2.5 [1] R: 2.1[1]

2

(b)i ii

RP [1] QR3 [1]

2

(c) P and R will form an ionic bond [1] as P is a non-metal with 7 valence electrons while R is a metal with 1 valence electron [1]

2

(d) R [1] 1 (e)

[1] Correct drawing of P & Q [1] [1] Correct number of electrons shared (1 Q atom to 3 P atoms)

2

Total 9