Name ____________________________ Date _______________ Period _______
Pre-AP Chemistry
Chemical Bonding Study Guide Key
1. Electrons involved in bonding are called ___Valence Electrons___.
2. Define electronegativity. EN is the ability of an atom to attract electrons in a
chemical bond.
3. List 2 ways that electronegativity is important to bonding. 1) it determines the
polarity of bonds 2) EN determines the type of bond formed (ionic vs covalent)
4. What is meant by the term percent ionic character? What does this tell us about
all bonds? % ionic character refers to the degree of sharing of electrons 100%
ionic = no sharing 0% ionic = sharing equally All bonds have some degree of
ionic character except atoms bonded to themselves.
5. Why do atoms come together to form bonds? (2 reasons) 1) it gives atoms an
octet in their valence shell 2) it lowers the potential energy of atoms
6. Explain the role of electrons in ionic, covalent and metallic bonding. What types
of atoms are involved in each type? Ionic- e- are given or received (btwn metal
and nonmetal) Covalent- e- are shared (btwn nonmetals) Metallic- a “sea” of
delocalized electrons causes free movement of electrons between empty orbitals
(btwn metals)
7. How is the octet rule important in drawing Lewis structures? Must make sure all
atoms have 8 electrons around them once bonded (exceptions: H=2 , B=6 Be=4)
8. How many valence electrons are in the following elements: C 4, S 6, Cl 7, B 3, Be
2, H 1
9. What happens to the potential energy of atoms once they bond? It decreases.
10. How is the chemical formula of an atom different from a molecular formula? The
molecular formula describes how many atoms are in a single unit (molecule). The
chemical formula may sometimes only represent the ratio of atoms in a structureas in ionic bonds that form a lattice.
11. Why are metals good conductors of electricity? Their electrons are not localized
around one atom. They move freely between several atoms. Electricity, by
definition, is the flow of electrons.
12. What is resonance? What types of bonds experience resonance? Resonance
occurs when one Lewis structure is not adequate to represent the true structure of
a molecule. The result of resonance are bonds that are equal in length, but the
length is between single and double bonds. Structures with multiple bonds
experience resonance.
13. What does a lattice energy or heat of vaporization tell you about the strength of a
bond? The lattice energy or heat of vap. Tells how much energy is required to
break bonds (intramolecular!)
14. Explain why diamonds have very high melting temperatures despite the fact that
the bonds are covalent. Diamonds have a high melting temp because the C atoms
form network covalent bonds. This means that all carbons are covalently bonded
to several other carbons in the structure. The bonds broken are covalent, which is
different than most other molecules that have IMF broken when changing states
of matter.
15. Why do covalent bonds generally have lower melting temperatures but are
stronger than ionic bonds? Usually IMF are being broken, not the covalent bonds.
When ionic compounds melt, ionic forces must be broken, which requires much
more energy than breaking IMF.
16. What does VSEPR stand for? Why is it important? Valence Shell Electron Pair
Repulsion theory It dictates the shape of molecules based on the fact that
electrons and lone pairs of electrons repel each other due to charge.
17. Predict the shapes of the following species: (Hint: Draw the LEWIS
STRUCTURE!!)
a. SbF6-1 Octahedral
b. PCl3 trigonal pyramidal
c. SO3-2 trigonal planar
d. H2Se bent
e. XeO3 trigonal planar
18. Compare and contrast intermolecular forces with intramolecular forces.
Intermolcular forces are between molecules while intramolecular forces are
within molecules (the forces that keep atoms together). Both involve interactions
based on differences in charge.
19. Compare and contrast polar versus nonpolar covalent bonds. Both involve
sharing of electrons and occur between nonmetals. However, polar molecules
have uneven sharing of e-, while nonpolar share e- evenly.
20. Can you have a molecule that is nonpolar that has polar bonds in it? Give an
example. Yes! The dipole moments can cancel out! CO2
21. List the three types of intermolecular forces. Dipole-dipole, hydrogen bonding,
and London dispersion forces (aka van der Waals).
22. Describe each of the following in terms of intermolecular forces: CN-1, SO2, CH4,
SF6, CH3OH dipole-dipole, dipole-dipole, London dispersion, London dispersion,
hydrogen bonding
23. Draw Lewis structures for the following (be sure to tell whether they are ionic or
covalent first!!!) Show resonance where applicable!!!!
a. BH3 3 bonds, no lone pairs
b. SiO2 two double bonds, no lone pairs on Si
c. BaCl2 ionic
d. K2Se ionic
e. CH3COO-1 C bonded to three H and another C. 2nd C double bonded to
one O and single bonded to the other (there is resonance there!)
f. ClO-1 Single bond with 3 lone pairs around each atom
g. NH4+ Single bonds between H and N. N has 4 H bonded to it.
h. C2N2 C in center, single bond between C atoms. N on each end of
molecule. N are triple bonded to C on each side and each N has one lone
pair.