Part 11 Answer the following questions 16 Write Lewis dot symbols for the following atoms and ions :mg , Na, B , N, Br Be, Li^+,Cl^-,O^2-,Mg^2+ and N^3- 17. List four major difference between sigma (sigma ) and pi (pi ) bonds. 18 . Which one is stronger:o-bond or To -bond?? Why? 19 Explain why a BeH_(2) molecule has a zero dipole moment although the Be -H bonds are polar? 20 . How can one non-polar molecule induce a dipole in a nearby non -polar molecule? 21 . Describe the change in hybridization of an aluminum atom lif any)during the reaction: AlCl_(3)+Cl^-arrow AlCl_(4)^- 22 . Apart from tetrahedral geometry,another possible geometry for CH_(4) is square planar with the four H atoms at the corners of the square and C atom at its center. Explain why CH_(4) is not square planar? 23 . Sketch the bond moments and resultant dipole moments in the following molecules: H_(2)O,PCl_(3),NH_(3),NF_(3) 24.Write the resonance structures for SO_(2),NO_(2) and NO_(3)^-.S

16. Lewis dot symbols for the given atoms and ions:<br />- Mg: [Mg] with no dots around it.<br />- Na: [Na] with one dot around it.<br />- B: [B] with three dots around it.<br />- N: [N] with five dots around it.<br />- Br: [Br] with seven dots around it.<br />- Be: [Be] with two dots around it.<br />- Li⁺: [Li] with no dots around it.<br />- Cl⁻: [Cl] with eight dots around it.<br />- O²⁻: [O] with eight dots around it.<br />- Mg²⁺: [Mg] with no dots around it.<br />- N³⁻: [N] with eight dots around it.<br /><br />17. Four major differences between sigma (σ) and pi (π) bonds:<br />- Sigma bonds are single covalent bonds, while pi bonds are double or triple covalent bonds.<br />- Sigma bonds are formed by the head-to-head overlap of atomic orbitals, while pi bonds are formed by the side-to-side overlap of atomic orbitals.<br />- Sigma bonds are stronger and shorter than pi bonds.<br />- Sigma bonds allow rotation, while pi bonds do not.<br /><br />18. The sigma (σ) bond is stronger than the pi (π) bond. This is because sigma bonds involve the direct overlap of atomic orbitals, resulting in a stronger bond. Pi bonds, on the other hand, involve the side-to-side overlap of atomic orbitals, which is less effective in creating a strong bond.<br /><br />19. The BeH₂ molecule has a zero dipole moment despite the polar Be-H bonds because the molecule is linear. The two polar Be-H bonds are symmetrically arranged around the Be atom, causing their dipole moments to cancel each other out.<br /><br />20. A non-polar molecule can induce a dipole in a nearby non-polar molecule through temporary fluctuations in electron density, known as London dispersion forces. These temporary dipoles can cause a temporary imbalance in electron distribution in the nearby non-polar molecule, inducing a dipole moment.<br /><br />21. In the reaction AlCl₃ + Cl⁻ → AlCl₄⁻, the aluminum atom undergoes a change in hybridization from sp² to sp³. This is because the addition of the chloride ion (Cl⁻) to the aluminum atom results in the formation of a tetrahedral geometry, requiring the use of sp³ hybrid orbitals.<br /><br />22. CH₄ is not square planar because the carbon atom forms four equivalent sigma bonds with the hydrogen atoms, resulting in a tetrahedral geometry. In a square planar geometry, the bond angles would be 90 degrees, which is not the case in CH₄.<br /><br />23. Bond moments and resultant dipole moments in the given molecules:<br />- H₂O: The oxygen atom is more electronegative than the hydrogen atoms, resulting in a dipole moment pointing towards the oxygen atom.<br />- PCl₃: The chlorine atoms are more electronegative than the phosphorus atom, resulting in dipole moments pointing towards the chlorine atoms.<br />- NH₃: The nitrogen atom is more electronegative than the hydrogen atoms, resulting in a dipole moment pointing towards the nitrogen atom.<br />- NF₃: The nitrogen atom is more electronegative than the fluorine atoms, resulting in a dipole moment pointing towards the nitrogen atom.<br /><br />24. Resonance structures for SO₂, NO₂, and NO₃⁻:<br />- SO₂: <br /> Structure 1: S=O-O<br /> Structure 2: S-O=O<br />- NO₂:<br /> Structure 1: O=N-O<br /> Structure 2: O-N=O<br />- NO₃⁻:<br /> Structure 1: O-N=O<br /> Structure 2: O-N⁺-O⁻<br /> Structure 3: O-N⁺-O⁻