Chapter 20.1, Problem 2RQ

a.

Interpretation Introduction

Interpretation: The shape of CH₄ molecule is to be determined.

Concept Introduction: The shape of a molecule depends on the hybridization of its central atom.

Answer to Problem 2RQ

The shape of CH₄ molecule is tetrahedral.

Explanation of Solution

  

Electronic configuration of carbon is $1s^{2}2s^{2}2p^2$ . To share each electron with hydrogen one electron from 2s orbital is excited to 2p orbital and now, one 2s and three 2p orbitals hybridise to form four $s{p}^3$ orbitals. So, its hybridisation is $s{p}^3$ and geometry is tetrahedral.

Ground state configuration:

  

Excited state configuration:

  

b.

Interpretation Introduction

Interpretation: The shape of CH₂O molecule is to be determined.

Concept Introduction: The shape of a molecule depends on the hybridization of its central atom.

Answer to Problem 2RQ

The shape of CH₂O molecule is trigonal planar.

Explanation of Solution

  

Electronic configuration of carbon is $1s^{2}2s^{2}2p^2$ . To share each electron with hydrogen and oxygen one electron from 2s orbital is excited to 2p orbital and now, one 2s and two 2p orbitals hybridise to form three $s{p}^2$ orbitals. And one unhybridised 2p is involved in formation of double bond. So, its hybridisation is $s{p}^2$ and geometry is trigonal planar.

Ground state configuration:

  

Excited state configuration:

  

c.

Interpretation Introduction

Interpretation: The shape of C₂H₂ molecule is to be determined.

Concept Introduction: The shape of a molecule depends on the hybridization of its central atom.

Answer to Problem 2RQ

The shape of C₂H₂ molecule is linear.

Explanation of Solution

  

Electronic configuration of carbon is $1s^{2}2s^{2}2p^2$ . To share each electron with hydrogen and other carbon one electron from 2s orbital is excited to 2p orbital and now, one 2s and one 2p orbital hybridise to form two $sp$ orbitals. And two unhybridised 2p are involved in formation of two $\pi$ bonds. So, its hybridisation is $sp$ and geometry is linear.

Ground state configuration:

  

Excited state configuration: