Untitled - Kelly Walsh High School

Chemical Bonding 141
Quick Tip
Elements in the first two rows on the periodic table will never exceed an octet.
If they are exceptions to the octet rule, they will have less than an octet.
Lewis symbols and structures are a type of structural formula in which shared
pairs of electrons are represented by dashes and unshared electrons are shown
as dots. The Lewis structure may be generated by the use of the N A S rule
(assuming the octet rule is obeyed). The electronegativity of an element is the
measure of the attraction that an element has on the electrons in a bond. If
the difference in electronegativity between the two elements sharing one or
more electron pairs is greater than 1.7, the bond is classified as ionic, less
than 1.7 polar covalent and 0 pure covalent. Resonance occurs when there is
more than one equivalent Lewis structure possible for a molecule. In general,
single bonds are longer and weaker than double bonds, while triple bonds are
the shortest and strongest.
1. State the octet rule.
2. What does isoelectronic mean?
3. How many electrons should the Lewis symbols of each of the following elements
indicate?
a.K b.Ar c.I d.N e.Si
4. What is the definition of electronegativity?
5. Which of the following pairs of elements will have the greatest difference in
electronegativity?
a. B and C b. C and Si c. O and F d. F and S e. Cl and Si
6. Which of the following is not following the octet rule?
a. F b. O c. P 3 d. Mg 2 e. Ti 4
7. How many electrons must each of the following gain to achieve an octet?
a. S b. I c. Ar
8. How many electrons must each of the following lose to achieve an octet?
a. Cs b. Mg c. Cl
9. What is the definition of lattice energy?
10. What is the maximum number of covalent bonds between a pair of atoms?
a. 1 b. 2 c. 4 d. 3 e. 6
11. Which type of bond will form between two nonmetals that differ slightly in
electronegativity?
a. polar covalent b. nonpolar covalent c. ionic
d. metallic e. no bond can form