Bonding Frq’s AP chem
I
A. Magnesium chloride is an ionic solid with strong electrostatic attractions between a +2 and a – 2
ion, silicon tetrachloride is composed of non polar molecules with weak dispersion forces as the
primary IMF. Dispersion forces require much less energy to overcome than the coulombic
attraction between ions.
B. Magnesium chloride and magnesium fluoride are both ionic solids with strong coulombic
attractions between ions. The attraction in mgF is greater because the F- ion is smaller than the
cl- ion and attraction increases as distance between charged particles decreases.
C. F2 and Br2 both contain single covalent bonds formed from the overlap of a p orbital. The bond
in br2 is achieved with a 4 p orbital f2 with a 2p orbital. 4 p orbitals are at much greater
distance from the nucleus so the bond is longer
D. F2 is a should be a smaller molecule since n is smaller than f, however N2 contains 1 sigma and 2
pi bonds which make the bond much smaller than the sigma bond of f2.
II
A. Ammonia is polar molecule with a negative end at the N and positive ends at the H’s and
since N is small and highly electroneg. The molecule is polar enough for Ammonia to exhibit
hydrogen bonding as its primary IMF while methane is a nonpolar substance with weak
dispersion forces b/t molecules. It takes more energy to overcome the h bonds in ammonia
than the dispersion forces in methane
B. Ethane and hexane are both non polar molecules with weak dispersion forces between
molecules however hexane is a more polarizable molecule containing more electrons than
ethane. The more electrons in a molecule the more momentary dipoles form so attractions
are greater.
C. Si is a network solid with strong single covalent bonds throughout, Cl2 is composed of non
polar molecules with weak dispersion forces. It takes far more energy to break a covalent
bond than it does to overcome dispersion forces
D. MgO and NaF are both ionic solids with a strong coulombic attraction b/t the ions. However
attraction increases as the charge of the ions increases. MgO has +2 and -2 which attract
better than the +1 – 1 in NaF
III
B i propane is a non polar hydrocarbon with weak dispersion forces throughout the sample
Propanone is a weakly polar molecule with dipole dipole attractions that are stronger than
the dispersion forces in propane. The stronger the attractive forces the more energy that
needs to be added to vaporize a substance
Ii Propanone and propanol are both polar molecules however propanol is more polar due to
the OH group at the end of the molecule. The OH group is also capable of Hydrogend
bonding with other OH groups. Hydrogen bonds require more energy to overcome than the
dipole dipole attractions of propanone.
IV
A) f2 and i2 both nonpolar
Both have weak dispersion forces
I2 more electrons = more momentary dipoles= more energy to overcome
B )Ionic solids
Both have strong attraction between ions
Both are +1 – 1, so smaller ions NaF have greater attraction than larger ones CsCl
C ) ICl4 - has 4 bonds 1 lone pair
BF4- has 4 bonds no lone pairs
D) ammonia hydrogen bonds with water H to O, pH3 is polar but not as polar so the
attractions b/t water is less.
VI
C in so2 there is resonance, more than 1 structure is needed to portray the molecule, as a
result the bond length in So2 is an average of single and double bonds making them all the
same length