Question

(a) According to the Valence Bond (VB) theory applied to the molecule of methane (CH4): (i) Identify the type of hybridization of the carbon atoms. Justify your answer by drawing the promotion/hybridization scheme for carbon. [4 marks] (ii) Identify and sketch the spatial orientation of the hybrid orbitals and discuss the type of chemical bonds in the molecule. [3 marks]

(b) With reference to the molecule of sulfur tetrafluoride (SF4): (i) Determine the oxidation number of each element. [1 marks] (ii) Draw and justify its Lewis structure. [3 marks] (iii) Calculate the formal charge for each atom. [1 mark] (iv) Use the VSEPR model to predict the molecular geometry, the FSF angles and the polarity of the molecule. Justify your statements. [6 marks]

Answer 1

1 (i) sp3 hybridzation to explain the bonding in the tetrahedral methane .. the idea valence bond theory is that good overlap b/w the atomic orbitals centred oncarbon and hydrogen lead to strong bond

the carbon atoms will and then hybridise to give sp3 hybrid . the carbon atom will join to each other by joining sigma bonds by the end to overlap of sp3 orbitals

(ii)

2 ( i) oxidation state of s is =+4 and f=-1

(ii)

(iii) formal charge of s is +2

(iv) the vsepr geometry of sf4 is trigonal bipyramidal and see saw shape