Chapter 3: Intermolecular Bonding

Question 1

Shapes of Molecules

Answer 1

• Linear -> 180degrees
• trigonal planar -> 120 degrees
• Tetrahedral -> 109.5 degrees
• Pyramidal -> approx 109.5 degrees
• Bent / v-shaped -> 120 degrees

Question 2

Non-polar bonds

Answer 2

• Covalent bonds b/w two identical atoms i.e Cl2
• electrons are shared equally between two atoms
• where electrons spend equal time moving around the atom. Cl-Cl
• > where - = bond

Question 3

Polar bonds

Answer 3

• Covalent bond b/w two different atoms
• Electrons are not equally shared
• electrons spend more time around atom w/ higher electronegativity therefore partial -ive charge.

Question 4

Non- polar molecules

Answer 4

• Molecule has no net dipole
• molecule has only non polar bonds
• vector sum of all electrical dipoles is zero
• has dispersion forces only
  IS SYMMETRICAL
• linear
• trigonal planar
• tetrahedral

Question 5

Polar molecules

Answer 5

• Molecule has assymetrical charge distribution
• has dispersion forces and dipole-dipole forces
• Have uneven charge distributions

Question 6

Dispersion Forces

Answer 6

• The attraction b/w the instantaneous dipole of a molecule with the attraction b/w another instantaneous dipole
• Occur b/w all molecules
• More electrons a molecule has, more disperion forces it has
• are forces only due to temporary dipole
• influenced by size of molecule -> greater chance electrons arranged asymmetrically( stronger)
• shape of molecule -> larger surface area which electrons can develop instantanouse dipole ( stronger disperson forces)

Question 7

Dipole- Dipole Forces

Answer 7

• Weak attractive forces b/w polar molecules
• occur because part of molecule slightly positive attracted to slightly negative part of another
• the more polar, the stronger the dipole dipole forces

Question 8

Hydrogen bonding

Answer 8

• Exist in POLAR molecules that contain: N-H, F-H, O-H

- A strong dipole-dipole force occurs as N,F,O are the most electronegative & much more electronegative than H

Question 9

Extreme Polar Bonds

Answer 9

• When two atoms with large differences in electronegativity combine
• high electronegativity takes ownership of an electron, therefore positive negative ions formed.

Question 10

Disperson vs dipole-dipole

Answer 10

• Disperson forces are weaker than dipole-dipole
• However, dispersion forces can become more significant than dipole-dipole forces
• e.g CCl4 and CH3Cl
• > CH3Cl has dispersion and dipole-dipole
• > CCl4 has more electrons however, therefore higher bp
• > Dispersion force stronger than both in CH3Cl