Covalent Bonding

Question 1

What are molecules? (1 mark)

Answer 1

⦾ (+) 2 atoms bonded together (1)

Question 2

What type of bonding are molecules held together by?

1 mark

Answer 2

⦾ Strong covalent bonds (1)

Question 3

What is a covalent bond? (2 marks)

Answer 3

⦾ 2 atoms share e-s (1)

⦾ To achieve full outer shell (1)

Question 4

What is a single covalent bond? (2 marks)

Answer 4

⦾ Both +ve nuclei attracted electrostatically attracted to (1)
⦾ Shared pair of e- (1)

Question 5

What do the lines in displayed formula represent?

1 mark

Answer 5

⦾ Covalent bonds (1)

Question 6

1. What are double bonds? (2 marks)

2. Give an example? (1 mark)

Answer 6

1. ⦾ Share 4 e- (1)
   ⦾ 2 e- from each atom (1)
2. CO2 (1)

Question 7

1. What is a triple bond? (2 marks)

2. Give an example? (1 mark)

Answer 7

1. ⦾ Atoms share 6 e- (1)
   ⦾ 3 e- from each atom (1)
2. N2

Question 8

What are simple covalent compounds? (3 marks)

Answer 8

⦾ Compounds made up of lots of individual molecules (1)
⦾ Individual molecules held by strong covalent bonds (1)
⦾ Molecules within held by weak IMFs (1)

Question 9

Which bonds in intermolecular forces determines their properties? (1 mark)

Answer 9

⦾ IMFs (1)

Question 10

What are Giant Covalent Structures? (2 marks)

Answer 10

⦾ Crystal structure type (1)

⦾ Huge network of covalently bonded atoms (1)

Question 11

What can Giant Covalent Structures also be called?

1 mark

Answer 11

⦾ Macromolecular structures (1)

Question 12

What is the structure of graphite? (4 marks)

Answer 12

⦾ 3 X C covalent bonds (each) (1)
⦾ (Flat) hexagonal sheets (arranged) in layers (1)
⦾ 4th e- delocalised (1)
⦾ VWFs between sheets (1)

Question 13

Explain how graphite’s structure relates to its properties and uses? (10 marks)

Answer 13

1 ⦾ Weak VWFs between layers - sheets slide over each other + slippery e.g. dry lube in pencils (2)
2 ⦾ Delocalised e- free to move along sheets - electric current flows (2)
3 ⦾ Far apart layers compared ton covalent bond lengths - low density e.g. light-weight sports equipment (2)
4 ⦾ Strong covalent bonds - v. high mp. (2)
5 ⦾ Insoluble - v. strong covalent bonds in sheets (2)

Question 14

What is the structure of Diamond? (2 marks)

Answer 14

⦾ 4 X C covalent bonds (each) (1)

⦾ (arranged) tetrahedral shape (crystal lattice) (1)

Question 15

Explain how diamond’s structure related to its properties and uses? (10)

Answer 15

⦾ V. high mp. - strong covalent bonds (2)
⦾ V. hard - strong covalent bonds e.g. diamond-tipped drills and saws (2)
⦾ Good thermal conductor - vibrations travel easily through stiff lattice (2)
⦾ Can’t conduct electricity - no delocalised e- (2)
⦾ Insoluble - strong covalent bonds (2)

Question 16

What is a co-ordinate/dative covalent bonding? (1 marK)

Answer 16

⦾ 1 atom provides both shared e-s (1)

Question 17

How is an Ammonium ion formed? (1 mark)

Answer 17

⦾ Co-ordinate bonding (1)

Question 18

Explain the formation of an Ammonium ion? (1 mark)

Answer 18

⦾ N in NH3 donates e- pair to H+ (proton) (1)

Question 19

How can co-ordinate bonding also be shown in diagrams? (2 marks)

Answer 19

⦾ Arrow (1)
⦾ Point away from donor atom (1)
(pg. 75)
       H         +
        I
[H - N → H]
        I
       H

Question 20

Explain the formation of Hydroxonium ion?

Answer 20

⦾ H2O + H+ → H3O+
⦾ O in H2O has 2 lone e- pairs
⦾ H+ are e- defficient
⦾ O donates 1 lone e- pair to H+ forming dative bond

[H - O → H] +
I
H