Chemistry Class 11 NCERT Solutions: Chapter 11 the p Block Elements Part 2

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Q: 7. Describe the shapes of and . Assign the hybridisation of boron in these species.

Q 7 Structure of Hybridisation of Boron in These Species

Q 7 Structure of Hybridisation of Boron in These Species

Q 7 Structure of Hybridisation of Boron in These Species

Answer:

(i)

As a result of its small size and high electronegativity, boron tends to form monomeric covalent halides. These halides have a planar triangular geometry. This triangular shape is formed by the overlap of three hybridised orbitals of boron with the orbitals of three halogen atoms. Boron is hybridised in .

Q 7 i Structure of Boron Trifluoride of P orbital

Q 7 I Structure of Boron Trifluoride of P Orbital

Q 7 i Structure of Boron Trifluoride of P orbital

(ii)

Boron – hydride ion is formed by the hybridisation of boron orbitals. Therefore, it is tetrahedral in structure.

Q 7 ii Structure of Boron-hydride ion

Q 7 Ii Structure of Boron-Hydride Ion

Q 7 ii Structure of Boron-hydride ion

Q: 8. Write reactions to justify amphoteric nature of aluminium.

Answer:

A substance is called amphoteric if it displays characteristics of both acids and bases. Aluminium dissolves in both acids and bases, showing amphoteric behaviour.

(i)

(ii)

Q: 9. What are electron deficient compounds? Are and electron deficient species? Explain.

Answer:

In an electron-deficient compound, the octet of electrons is not complete, i.e., the central metal atom has an incomplete octet. Therefore, it needs electrons to complete its octet.

(i)

is an appropriate example of an electron – deficient compound. B has 3 valence electrons. After forming three covalent bonds with chlorine, the number of electrons around it increases to 6. However, it is still short of two electrons to complete its octet.

Q 9 i Structure of Boron Trichloride

Q 9 I Structure of Boron Trichloride

Q 9 i Structure of Boron Trichloride

(ii)

The electronic configuration of silicon is this indicates that it has four valence electrons. After it forms four covalent bonds with four chlorine atoms, its electron count increases to eight. Thus, SiCl4 is not an electron deficient compound.

Q 9 ii Structure of Silicon Tetrachloride

Q 9 Ii Structure of Silicon Tetrachloride

Q 9 ii Structure of Silicon Tetrachloride

Q: 10. Write the resonance structures of .

Answer:

(A)

Q 10 A Structure of Carbonate Ion

Q 10 a Structure of Carbonate Ion

Q 10 A Structure of Carbonate Ion

(B)

Q 10 B Structure of Bicarbonate Ion

Q 10 B Structure of Bicarbonate Ion

Q 10 B Structure of Bicarbonate Ion

There are only two resonating structures for the bicarbonate ion.