Covalent structure (2) Shapes & polarity questions
Assignment: Questions on Topic 4.3: Shapes & polarity
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Predict the shape and bond angles of:
i. boron trichloride, BCl3
ii. phosphoryl chloride, POCl3
iii. phosphine, PH3
iv. hydrogen cyanide, HCN
Explain why sulfur dioxide molecules, SO2, have a bent shape whereas carbon dioxide molecules, CO2, are linear
Explain why C=O bonds are polar and yet the carbon dioxide molecule is non-polar.
Explain why the H-N-H angle in ammonia is smaller than the H-N-H angle in the ammonium ion.
A simplified model of benzene, C6H6, shows the six carbon atoms in a ring with alternate single and double bonds between the carbon atoms. Each carbon atom is also bonded to one hydrogen atom.
i. Based on the model described above predict the bond angle in benzene.
ii. In cyclohexane, C6H12 the six carbon atoms are also in a ring but are joined to each other only by single bonds. Each carbon atom is also bonded to two hydrogen atoms. Predict the bond angle in cyclohexane.
Fluorine and oxygen are very electronegative elements. Explain why hydrogen fluoride, HF, and water, H2O, are very polar molecules but tetrafluoromethane, CF4, and carbon dioxide, CO2 are non- polar.
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Predict the shape of:
i. xenon tetrafluoride, XeF4
ii. the iodine tetrachloride ion, ICl4–
iii. chlorine trifluoride, ClF3
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Predict all the bond angles in:
i. phosphorus pentafluoride, PF5
ii. the phosphorus hexafluoride ion, PF6–