PSI AP Chemistry: Chemical Bonding
Chapter Problems Part A Covalent Compounds
Name _______________________
1. The bond between atoms of O and C is referred to as being polar covalent?
a. Why is this bond considered covalent and not ionic?
b. Why is the bond considered polar covalent instead of nonpolar covalent?
c. Which atom in the bond carries the partial positive charge? Explain.
d. Provide an element O could bind with to create an ionic bond. Justify your
answer.
e. Provide an element O could bind with to create a nonpolar covalent bond.
Justify your answer.
f. What causes the attraction between the atoms in this C-O bond?
g. What would happen to the potential energy of the atoms if they got too
close to each other? Explain your answer.
2. Explain the following observations:
a. The lattice energy of LiF is 1036 kJ/mol while that of LiCl is 897 kJ/mol.
b. The N-H bond length is 98 pm while that of P-H is 140 pm.
c. The N-H bond length is 98 pm while that of O-H is 94 pm.
d. The lattice energy of MgO is higher than that of MgF2.
3. Propose a reason as to CaCl2 may be soluble in water while CaF2 would not
be?
4. Examine the figure below:
a. What is the approximate bond length for these atoms represented
in the diagram?
b. What is the approximate bond energy for these atoms in the
diagram?
c. Why is the potential energy of the atoms higher as the distance
between the atoms increases?
d. Why does the potential energy of the atoms increase sharply as the
inter-nuclear distance becomes very small?
e. Is bond formation exothermic or endothermic? Explain your
answer.
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Chemical Bonding
Answers
1.
a. The electronegativity difference is too small for ion formation so
electrons are shared instead.
b. The electronegativity difference is such that the electrons are shared
unequally with the O atom pulling more strongly and possessing the
electrons a greater share of the time
c. C would, as it has the smaller electronegativity.
d. A metal with a small electronegativity like Ca or Rb would be excellent
choices, this creates a large enough electronegativity difference to
induce ion formation.
e. Ideally, itself – as this would create a zero electronegativity difference.
f. The shared electrons between the nuclei result in an attraction
between them.
g. The potential energy would increase as the repulsions between the
positive nuclei would increase dramatically.
2.
a. The chloride ion has a larger ionic radii than does fluoride resulting
in weaker Coulombic attractions and a smaller lattice energy.
b. The P atom has a higher atomic radii making the Coulombic
attractions weaker and the bond length longer.
c. Two reasons. The radii of O is smaller than that of N thereby creating
stronger Coulombic attractions but also the bond between O-H is more
polar which creates a stronger Coulombic attraction as well.
d. The charge density is considerably higher in the oxide ion compared
to that of a fluoride ion (-2 to -1) resulting in stronger Coulombic
attractions.
5. The lattice energy of CaF2 is considerably higher due to the smaller ionic
radii of the fluoride ion. This would make dissociation harder in aqueous
solvents.
6.
a. 33 pm
b. -210 kJ/mol
c. The attractions between the atoms diminishes as the distance
increases.
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Chemical Bonding
d. The repulsions between like charged nuclei increase
significantly
e. Exothermic, as atoms lower their potential when forming
attractions thereby releasing energy to the surroundings.
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AP Chemistry
Chemical Bonding