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Question
Describe the general trends in the following properties of the elements in Groups 13 and 14.
Nature of halides
Solution
Except thallium, All the elements of the boron family combine with three atoms of halogens to form trihalides. All these halides exist as molecular species with hybridisation of sp2. All the trihalides are Lewis acid and their acidic strength of trihalides of boron is in order: Bf3 < BCl3 < BBr3 < Bl3. In group-14, except carbon, all group 14 elements on reaction with halogens form tetra halides where central metal atom shows the sp3 hybridisation state and corresponding tetrahedral shape.
There are few exceptions also, SnF4 and Pf4 are ionic in nature, while the rest are covalent compounds.
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RELATED QUESTIONS
If B–Cl bond has a dipole moment, explain why BCl3 molecule has zero dipole moment.
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Explain the following:
Boron does not exist as B3+ ion.
Explain the following:
PbX2 is more stable than PbX4.
Match the species given in Column I with the properties mentioned in Column II.
| Column I | Column II |
| (i) \[\ce{BF^{-}4}\] | (a) Oxidation state of central atom is +4 |
| (ii) AICI3 | (b) Strong oxidising agent |
| (iii) SnO | (c) Lewis acid |
| (iv) PbO2 | (d) Can be further oxidised |
| (e) Tetrahedral shape |
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PbO2 is a stronger oxidising agent than SnO2
Account for the following observations:
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