CHEMICAL BONDING

1. Compound X and Y have the following properties ; Both are covalent Both have the same type intermolecular forces Compound X has higher boiling point than YX and Y could be

X YA HF HClB HF NH3

C HCl HID HBr NH3

2. Which statements explain accurately why iodine is a solid whereas fluorine is a gas at room temperature?A. Iodine molecule is larger than that of fluorineB. The boiling point of iodine is higher than that of

fluorineC. The covalent bond in iodine is stronger than that

of fluorineD. The van der Waals forces in iodine molecules

are stronger than those in fluorine molecules.

3. Which of the following compound is the most electrovalent?A. BeCl2 C. AlCl3

B. SiO2 D. CaO

4. Which of the following molecules is polar?A. SF6 C. SnCl4

B. BCl3 D. CH3Cl

5. The shape of ICl4- ion is

A. Tetrahedral C. Octahedral B. Square planar D. Square pyramidal

6. What type of hybrid orbitals would tin used in SnCl3

-?A. sp C. sp3

B. sp2 D. sp3d

7. Which of the following structures represents the SnCl2 molecule?

8. The diagram below shows liquid chlorobenzene flowing from a burette near an electrically charge rod.

Which of the following could explain the effect of the charged rod on the jet of chlorobenzene?

Positively charged rod

Negatively charged rod

A Repelled Repelled B Attracted Attracted C Attracted Repelled D Repelled Attracted

9. In which of the following molecules has the central atom, one lone pair of electrons?A. SiH4

B. BF3

C. I3-

D. XeCl4

10. Which of the following are features of the structure of metallic copper?1 Ionic bonds2 Delocalised electrons3 Lattice of ions

11. Which of the following observations can be explained in terms of hydrogen bonding?1 Ice is less dense than water2 Amino acids are water soluble3 The melting point of HI is higher than that of HBr

12. In which of the following compounds can coordinate covalent bonds be found?1 Al2Cl6

2 NH4NO3

3 Cu(NH3)4SO4

Structured and Essay

1. Explain the following observationsa) The melting point of AlF3 and PF3 are 1291 ◦C and -151◦C respectively.b) Ethanoic acid and methyl ethanoate are isomers and have the same relative molecular mass, 60.0. However, the

melting points of ethanoic acid and methyl ethanoate are 17 ◦C and -99◦C respectively.c) The carbon dioxide molecule, CO2 is linear but the sulphur dioxide molecule, SO2 is V-shaped.

2. a) The boiling points of group 15 hydrides are shown in the graph below.

i. What is the oxidation number of bismuth in BiH3?ii. Explain the increasing boiling points of the hydrides from PH3 to BiH3.

iii. Explain why the boiling point of ammonia is higher than that of PH3.

b) The ammonium ion, NH4+ , is formed when ammonia reacts with a proton, H+ .

i. Draw a Lewis structure of ammonia and the ammonium ion.ii. The H-N-H bond angles in ammonia and NH4

+ are 107◦ and 109.5◦ respectively. Explain the difference in these bond angle.

iii. Describe the bonding in ammonia,NH3 using orbital hybridisation.

3. a) What is the difference between the electron-pair geometry and the molecular geometry of a molecule. Use the ClF5 molecules as an example in your answer.b) Predict the electron-pair geometry and the molecular geometry of each of the following molecules and ions.

i. PCl5 iv. ClO2-

ii. CH3+ v. ClF3

iii. SF4

4. Write the resonance forms that describe the distribution of electrons ina) Nitrate (v) ion, NO3

-

b) Nitric(v) acid, HNO3

c) Methanoate ion, HCOO-

5. a) Explain what is meant by hydrogen bond?b) Describe how hydrogen bonding explains the following physical properties of water ;

i. high boiling pointii. low density in the solid state.

c) Draw dot-cross diagrams and predict the shape of each of the following speciesi. CO2

ii. H3O+

iii. H2S

6. a) Ethene, C2H4 , and ethane, C2H6 , are both hydrocarbons.i)State the hybridization of the carbon atoms in ethene and ethane.ii)Draw the three-dimensional shapes of the ethene and ethane molecules.

b)The carbon=carbon bond in ethene consists of one sigma bond and one pi bond.i)Explain what is meant by sigma bondii)Explain what is meant by pi bond.iii)State the type of orbital overlap that produces the carbon-carbon sigma bond and pi bond.

Answer

1. B2. D3. D4. D5. B6. C

7. B8. B9. A10. C11. B12. D

Structured and essay.

1. Tfdsg2. Gsg3. a) -The electron-pair geometry describes the location of electron pairs as predicted by VSEPR theory.

-The molecular geometry indicates the position of the atoms in the molecule.-In ClF5 there are six pairs of electrons around the chlorine.So, the electron-pair geometry is octahedral.-Because there are 5 bonding pairs and one lone pair, the molecular geometry is square pyramidal.

4. a) Nitrate (V) ion has three equivalent Lewis structures.

b) HNO3 has two equivalent Lewis structures.

c) methanoate ion has two equivalent Lewis structures.

5. a) 6. dsg