Bonding and Structure HL [94 marks]

1. [Maximum mark: 1]
Which atom is sp2 hybridized?

A. C in H2CO

B. C in CO2

C. N in CH3NH2

D. O in H2O [1]

2. [Maximum mark: 1]
Which atom does not obey the octet rule?

A. C in CO2

B. F in BF3

C. O in H2O

D. S in SF6 [1]

3. [Maximum mark: 1]
Which species has delocalized electrons?

A. OH−

B. H2CO

C. CO2

D. CO32− [1]
4. [Maximum mark: 1]
How many carbon atoms are sp3, sp2 and sp hybridized in the
molecule?

[1]

5. [Maximum mark: 1]
Which species has a square planar molecular geometry?

A. SF4

B. XeF4

C. CF4

D. PF4+ [1]

6. [Maximum mark: 1]
How many sigma (σ) and pi (π) bonds are present in hydrogen cyanide,
HCN?
 [1]

7. [Maximum mark: 1]
What is the hybridization of carbon and oxygen in methanol?

[1]

8. [Maximum mark: 1]
What is the number of sigma (σ) and pi (π) bonds in the molecule
(NC)2C=C(CN)2?
 [1]

9. [Maximum mark: 1]
What is the hybridization of the circled carbon, oxygen and nitrogen
atoms?

[1]
10. [Maximum mark: 1]
Which molecules have at least one sp2 hybridized atom?

I. CH3COOH

II. CH3COCH3

III. CH2CHCH2OH

A. I and II only

B. I and III only

C. II and III only

D. I, II and III [1]

11. [Maximum mark: 1]

Which can be represented with only one Lewis structure?

A. CH2O

B. C6H6

C. O3

D. NO3− [1]

12. [Maximum mark: 1]

Which molecule has an expanded octet?

A. CO

B. CO2
 C. SF2
[1]
D. SF4

13. [Maximum mark: 1]

Which overlap of atomic orbitals leads to the formation of only a sigma
(σ) bond?

I. s − p

II. p − p

III. s − s

A. I and II only

B. I and III only

C. II and III only

D. I, II and III [1]

14. [Maximum mark: 1]

What is the hybridization state and electron domain geometry around
the circled C, N and O atoms?
 [1]

15. [Maximum mark: 1]

How many sigma (σ) and pi (π) bonds are present in this molecule?

[1]

16. [Maximum mark: 1]

Which combination describes the PH4+ ion?
 [1]

17. [Maximum mark: 1]

Which combination describes the bonding and structure in benzoic
acid, C6H5COOH?

[1]

18. [Maximum mark: 1]

Which species have resonance structures?

I. Ozone, O3
II. Carbon dioxide, CO2
III. Benzene, C6H6
 A. I and II only

B. I and III only

C. II and III only

D. I, II and III
[1]

19. [Maximum mark: 1]

Which does not show resonance?

A. PO43–

B. C6H6

C. C6H12

D. O3 [1]

20. [Maximum mark: 1]

Which statement is correct?

A. Sigma bonds are formed only by the combination of s atomic

orbitals.

B. Pi bonds can be formed in the absence of sigma bonds.

C. Pi bonds are formed parallel to the axis between atoms.

D. Pi bonds are formed only by the combination of hybrid orbitals. [1]

21. [Maximum mark: 1]

Which species breaks the octet rule?
 A. PCl3
B. BF4−
C. SCl4
D. NH4+ [1]

22. [Maximum mark: 1]

Which species has bond angles of 90°?

A. AlCl4-

B. ICl4-

C. NH4+

D. SiCl4 [1]

23. [Maximum mark: 1]

In which group do both compounds contain delocalized electrons?

A. C6H10, C5H10
B. Na2CO3, NaOH
C. NaHCO3, C6H6
D. NaHCO3, C6H12 [1]

24. [Maximum mark: 1]

What is the hybridization of the numbered atoms in ethanoic acid?
 [1]

25. [Maximum mark: 1]

Which of the following is correct?

[1]

26. [Maximum mark: 1]

What is correct for PCl5?

[1]
27. [Maximum mark: 1]
Which molecules have sp2 hybridization?

I. C2H4

II. C4H10

III. C6H6

A. I and II only

B. I and III only

C. II and III only

D. I, II and III [1]

28. [Maximum mark: 1]

Which combination of shape and bond angle is correct for a molecule
of xenon tetrafluoride, XeF4?

[1]

29. [Maximum mark: 1]

Which combination correctly describes the types of hybridization
shown by the two carbon atoms labelled α and β and the oxygen
atom labelled γ in the molecule of paracetamol shown below?
 [1]

30. [Maximum mark: 1]

What is the correct number of sigma (σ) and pi (π) bonds in prop-2-
enenitrile, CH2CHCN?

[1]
31. [Maximum mark: 12]
The equations show steps in the formation and decomposition of ozone in the
stratosphere, some of which absorb ultraviolet light.

Step 1 O2 → 2O•

Step 2 O• + O2 → O3

Step 3 O3 → O• + O2

Step 4 O• + O3 → 2O2

(a) Draw the Lewis structures of oxygen, O2, and ozone, O3. [2]

(b) Outline why both bonds in the ozone molecule are the same
length and predict the bond length in the ozone molecule.
Refer to section 10 of the data booklet.

Reason:

Length: [2]
(c) Predict the bond angle in the ozone molecule. [1]

(d) Discuss how the different bond strengths between the oxygen
atoms in O2 and O3 in the ozone layer affect radiation reaching
the Earth’s surface. [2]

(e) Identify the steps which absorb ultraviolet light. [1]

(f ) Determine, showing your working, the wavelength, in m, of

ultraviolet light absorbed by a single molecule in one of these
steps. Use sections 1, 2 and 11 of the data booklet. [2]
 (g) Ozone depletion is catalysed by nitrogen monoxide, NO, which
is produced in aircraft and motor vehicle engines, and has the
following Lewis structure.

Show how nitrogen monoxide catalyses the decomposition of

ozone, including equations in your answer. [2]

32. [Maximum mark: 13]

Dinitrogen monoxide, N2O, causes depletion of ozone in the stratosphere.

Different sources of N2O have different ratios of 14N : 15N.

The Lewis (electron dot) structure of the dinitrogen monoxide molecule can be
represented as:
(a) Outline why ozone in the stratosphere is important. [1]

(b) Dinitrogen monoxide in the stratosphere is converted to

nitrogen monoxide, NO (g).

Write two equations to show how NO (g) catalyses the

decomposition of ozone. [2]

(c) State one analytical technique that could be used to determine

the ratio of 14N : 15N. [1]

(d) A sample of gas was enriched to contain 2 % by mass of 15N

with the remainder being 14N.

Calculate the relative molecular mass of the resulting N2O. [2]

(e) Predict, giving two reasons, how the first ionization energy of
15N compares with that of 14N. [2]

(f ) Explain why the first ionization energy of nitrogen is greater

than both carbon and oxygen.

Nitrogen and carbon:

Nitrogen and oxygen: [2]

(g) State what the presence of alternative Lewis structures shows

about the nature of the bonding in the molecule.
 [1]

(h) State, giving a reason, the shape of the dinitrogen monoxide

molecule. [1]

(i) Deduce the hybridization of the central nitrogen atom in the

molecule. [1]

33. [Maximum mark: 14]

Calcium carbide, CaC2, is an ionic solid.

(a) Describe the nature of ionic bonding. [1]

(b) Describe how the relative atomic mass of a sample of calcium

could be determined from its mass spectrum. [2]
(c) When calcium compounds are introduced into a gas flame a red
colour is seen; sodium compounds give a yellow flame. Outline
the source of the colours and why they are different. [2]

(d) Suggest two reasons why solid calcium has a greater density
than solid potassium. [2]

(e) Outline why solid calcium is a good conductor of electricity. [1]

(f ) Sketch a graph of the first six ionization energies of calcium.

[2]

(g) Calcium carbide reacts with water to form ethyne and calcium
hydroxide.
 CaC2(s) + H2O(l) → C2H2(g) + Ca(OH)2(aq)

Estimate the pH of the resultant solution.

[1]

(h) Describe how sigma (σ) and pi (π) bonds are formed.

[2]

(i) Deduce the number of σ and π bonds in a molecule of ethyne.

[1]

34. [Maximum mark: 7]

(a) Draw the shape of the pz orbital using the coordinates shown.
 [1]

(b) State the electron configuration of Fe3+. [1]

(c) Define the term ligand. [1]

(d) Explain why the complex [Fe(H2O)6]

3+
is coloured. [3]
 (e) The element selenium (Z = 34) has electrons in the 4s, 3d
and 4p orbitals. Draw an orbital box diagram (arrow-in-box
notation) to represent these electrons. [1]

35. [Maximum mark: 1]

Which property shows a general increase from left to right across
period 2, Li to F?

A. Melting point

B. Electronegativity

C. Ionic radius

D. Electrical conductivity [1]

36. [Maximum mark: 1]

Which is an f-block element?

A. Sc

B. Sm

C. Sn

D. Sr [1]
37. [Maximum mark: 1]
What is the empirical formula of a hydrocarbon with 75 % carbon and
25 % hydrogen by mass?

A. C3H

B. CH2

C. C2H6

D. CH4 [1]

38. [Maximum mark: 1]

How many moles of magnesium hydroxide are produced with 0.50 mol
of ammonia?

Mg3N2 (s) + 6H2O (l) → 3Mg(OH)2 (aq) + 2NH3 (aq)

A. 0.25

B. 0.33

C. 0.75

D. 1.5 [1]

39. [Maximum mark: 1]

How do the following properties change down Group 17 of the
periodic table?
 [1]

40. [Maximum mark: 1]

What volume of carbon dioxide, CO2 (g), can be obtained by reacting 1
dm3 of methane, CH4 (g), with 1 dm3 of oxygen, O2 (g)?

CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l)

A. 0.5 dm3

B. 1 dm3

C. 2 dm3

D. 6 dm3 [1]

41. [Maximum mark: 7]

A student determined the percentage of the active ingredient magnesium
hydroxide, Mg(OH)2, in a 1.24 g antacid tablet.

The antacid tablet was added to 50.00 cm3 of 0.100 mol dm−3 sulfuric acid, which
was in excess.
(a) Calculate the amount, in mol, of H2SO4. [1]

(b) Formulate the equation for the reaction of H2SO4 with Mg(OH)2. [1]

(c) The excess sulfuric acid required 20.80 cm3 of 0.1133 mol dm−3
NaOH for neutralization.

Calculate the amount of excess acid present. [1]

(d) Calculate the amount of H2SO4 that reacted with Mg(OH)2. [1]

(e) Determine the mass of Mg(OH)2 in the antacid tablet. [2]

(f ) Calculate the percentage by mass of magnesium hydroxide in

the 1.24 g antacid tablet to three significant figures. [1]
42. [Maximum mark: 5]
Table 8 of the Data Booklet shows the atomic and ionic radii of the elements.

(a) Describe and explain the trend in atomic radius across period 3. [3]

(b) A student formulates the following hypothesis: “If phosphorus

were to form a positive ion, P3+, its ionic radius would
−12
probably be between 110 × 10 m and

m.” Evaluate this hypothesis. [2]

−12
212 × 10

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