Revision questions bonding
1.
(Specpap)
(a) With the aid of molecules such as
NH3 , H2O, C2H6 and CH3-C –H
II
O
Discuss how the Valence Electron Shell Pair Repulsion (VSEPR) theory can be used to predict
the shapes of molecules. (10 marks)
(b) Discuss the origin of hydrogen bonding and explain, giving examples, how hydrogen bonding
causes water to have unusual properties. (7 marks)
( c) One of the main uses of water is as a solvent. Why is it such a good solvent and what sort of
substances will tend to dissolve in water? (3 marks)
2. (M98)
The physical and chemical properties of elements and their compounds vary across and down the
Periodic Table.
(a) State and explain the variation in atomic radius that occurs:
i. Across a period such as Na  Cl
ii. Down a group, such as Li  Cs
(6 marks)
(b) Elements on the left of the Periodic Table . eg Na, are good electrical conductors, whereas
those on the right of the Periodic Table, eg S, conduct electricity poorly or not all.
Account for these results in terms of the bonding present in these two elements. (4 marks)
(c) Write the formulae of the oxides of sodium, aluminium and sulfur and describe their
acid/base nature. (6 marks)
(d) In terms of atomic structure state and account for the following:
i. The difference in reactivity of sodium and potassium with chlorine.
ii. The difference in ease of oxidation or ability to change from negative ions into atoms
(i.e lose electron). (4 marks)
3. N98 (1) When potassium reacts with sulfur
A.
B.
C.
D.
a potassium atom gives two electrons to a sulfur atom
two potassium atoms each give one electron to a sulfur atom
a sulfur atom shares a pair of electrons with one potassium atom
a sulfur atom shares a pair of electrons with two potassium atoms
4. N98 (1) When the H-N-H bond angles in the species NH2-, NH3, NH4+ are arranged in order of
increasing bond angle (smallest bond angle first), which order is correct?
A.
B.
C.
D.
NH2-  NH3  NH4+
NH4+  NH3  NH2NH3  NH2-  NH4+
NH2-  NH4+  NH3
5. N98 (1) A solid has a melting point of 1440 C. It conducts heat and electricity. It does not dissolve
in water or in organic solvent. The bond between the particles is most likely to be
A. covalent
B. dipole-dipole
C. ionic
D. metallic
1
6. M99 (1) Which compound contains ionic bonds? MgBr2, CH2Cl2, CH3COOH, SiCl4.
7. M99 (1) When CH4, NH3, H2O, are arranged in order of increasing bond angle, what is the correct
order?
A. CH4, NH3, H2O
B. NH3, H2O, CH4
C. NH3, CH4, H2O
D. H2O, NH3, CH4
8. M99 (1) Which one of the following bonds is the most polar?
B. P –F
A. N-F
C. S – F
D. Cl – F
9. M99 (1) In which of the following pairs does the second substance have the lower boiling point?
A. F2, Cl2,
B. H2O, H2S
C. C2H6, C3H8
D. CH3OCH3, CH3CH2OH
10. M99 (2) This question refers to chemical bonding.
(a) Draw electron dot structures for methane, ammonia and water. Use these structures to
explain why the molecular bond angles decrease in the order
methane > ammonia > water
(7)
(b) Draw electron dot structures for N2 and F2 and explain why F2is much more reactive than N2.
(3)
(c) Explain why the melting point of the elements increase in the order: (5)
sodium < magnesium < aluminium < silicon
(d) Compare the polarity of the bonds N-Cl and C-Cl. Are the molecules NCl3 and CCl4 polar or
non-polar? In all your answers give your reasons. (5)
11. M99 (1) Which substance exhibits only ionic bonding?
A. NaNO3
B. H2SO4
C. NH4Cl
D. MgBr2
12. N99 (1) What type(s) of intermolecular forces is/are present in CH3OCH3?
A. dipole-dipole, hydrogen bonds and van der Waals’
B. dipole-dipole and van der Waals’ only
C. hydrogen bonds and van der Waals’ only
D. van der Waals’ only
13. N99 (1) Which compound is most ionic? HCl, KF, MgCl2 or Al2O3
14. N99 (1) Which of the following molecules is polar? Cl2 , BCl3 , NCl3, CCl4
15. M99 (1) Which compound contains both covalent and ionic bonds? Na2CO3, MgBr2, CH2Cl2,
CH3COOH?
16. M98 (1) All of the following can exhibit hydrogen bonding except
A. methane
B. methanol
C. methanoic acid
D. water
17. M98 (1) How do the bond angles between the hydrogen atoms and the central atom in H2O, NH3
and CH4 compare?
A.
B.
C.
D.
the bond angles in these three molecules are all the same.
The bond angles in CH4 are less than those in NH3 which are less than those in H2O
The bond angles in NH3 are less than those in CH4 which are less than those in H2O
The bond angles in H2Oare less than those in NH3 which are less than those in CH4
2
18. (specpap) Which one of the following statements is correct?
A. the energy absorbed when liquid ammonia boils is used to overcome the covalent bonds
within the ammonia molecule.
B. The energy absorbed when solid phosporus (P4) melts is used to overcome the ionic bonds
between the phosporus molecules
C. The energy absorbed when sodium chloride dissolves in water is used to form ions.
D. The energy absorbed when copper metal melts is used to overcome the non-directional
metallic bonds between the copper atoms.
19. M98 (1) Which one of the following molecules contains a triple bond?
A. HCN
B. C2H4
C. H2CO3
D. O2
20. M98 (1) The boiling points of CH4, C2H6 and C3H8 are –164 C, -98 C and – 42 C respectively. The
trend in these boiling points is best explained in terms of differences in the strength of
A. covalent bonds
B. dipole-dipole forces
C. hydrogen bonds
D. van der Waals’forces
21. M98 (2) Different physical properties of substances result from their different types of bonding and
intermolecular forces. Consider some of the elements in the halogen group of the Periodic Table
and their hydrides.
Cl2
Br2
I2
m.p.in C
- 101
-7
114
b. p in C
-35
59
184
Mr
70.9
159.8
253.8
HCl
HBr
HI
b.p. in C
-85
-67
-35
Mr
36.5
80.9
127.9
(a) (i) Name the type of bonding present in the molecules Clc, Br2 and I2. Explain why this bonding
occurs. (2)
(ii) What are the physical states of Cl2 and Br2 at 25 C? Account for each of these states in terms
of the data above. (3)
(iii) Astatine is the element found below iodine in the halogen group. Predict the physical state of
astatine at 25 C. (1)
(b) (i) State the trend in bond polarity of the hydrides above and account for this trend at the
atomic/molecular level. (2)
(ii) Account for the differences in boiling point of these hydrides in terms of their intermolecular
forces. (2)
(iii) The boiling point of Hf (Mr = 20.0) is 20 C. What feature causes this abnormal boiling point?
(1)
22. (N00)
(a) Give an example of each of the following substances, and use bonding theories to describe
the interactions between atoms, molecules and /or ions in each:
(i) a polar covalent substance
[5]
(ii) a network (giant) covalent solid [3]
(iii) a solid that contains both covalent and ionic bonds [4]
3
(b) Draw the molecular shape of aminoethane (CH3NH2) and predict the bond angles around the
carbon and nitrogen atoms using the Valence Shell Electron Repulsion (VSEPR) theory. [4]
(c) Aminomethane and ethane have similar molar masses. Explain why aminomethane has a
boiling point of – 6C whereas that of ethane is- 89C. [4]
23. (pre-98)
(a) Draw Lewis structures for the following: BF3, F2CO, HCN, HSCN, and NH4Cl.
(b) On the basis of the Lewis structures predict the shape of each species.
( c) Account for the shape of each species, using VSEPRT.
[5]
[2]
[3]
24. (N97) For the species CO2, H2CO3 and SO2,
(a) Write appropriate electron dot structures. [3]
(b) Determine the geometry and polarity, explaining your reasoning. [9]
25. Which pair of elements is most likely to form an ionic bond?
A. K and S
B. Si and O
C. N and Cl
D. H and F
26. What is the electron arrangement of the ion O2-?
A. 2,6
B. 2,8
C. 2, 8, 6
D. 2, 8, 8
27. An element is in group 3 and period 2. How many electrons are present in its outer shell?
A. 2
B. 3
C. 5
D. 6
28. Which statement is not true about metallic bonding?
A.
B.
C.
D.
It is present in mixtures of metals.
It results from the transfer of electrons from metals to non-metals.
It involves the delocalisation of electrons.
It is electrostatic in nature.
29. Chlorine has a lower boiling point than bromine because chlorine and bromine have
different
A. reactivities
B. bond enthalpies
C. bond polarities
D. molecular masses
30. Which one of the following compounds is non-polar?
A. HCl
31.
B. SCl2
C. CHCl3
D. CCl4
In which one of the following pairs are both substances ionic?
A. KCl, CaCl2
B. MgCl2, Cl2
C. COCl2, PCl3
D. NH4Cl, BCl3
4
32. Sulfur dioxide is polar whereas carbon dioxide is non-polar. Which of the following factors
contribute to this difference?
I.
II
A difference in the geometry of the molecules
A difference in the polarity of the bonds in the molecules
A. I only
B. II only
C. Both I and II
D. Neither I and II
C. tetrahedral
D. triangular
33. A molecule of PCl3 is best described as
A. pyramidal
B. T-shaped
34. An element with symbol Z has the electron configuration 2,8,6. Which species is this element most
likely to form?
A. The ion Z2+
B. the ion Z6+
C. The compound H2Z
D. The compound Z6F
35. Which of the following properties increase with increasing atomic number for fluorine and chlorine?
melting point of the elements boiling points of the hydrogen chlorides
A. I only
B. II only
C. Both I and II
D. Neither I nor II
5