Ch. 9 Homework Questions
1. Write Lewis dot symbols for atoms of the following elements:
(a) Be
(b) K
(c) Ca
(d) Ga
(e) O
(f ) Br
(g) N
(h) I
2. An ionic bond is formed between a cation (A+) and an anion (B-). How would the energy of
the ionic bond be affected by the following changes? (Refer to Coulomb’s law)
(a) doubling the radius of A+
(b) tripling the charge on A+
(c) doubling the charges on A+ and B(d) decreasing the radii of A+ and B- to half their original values.
3. Specify which compound in the following pairs of ionic compounds has the higher lattice
energy: (a) KCl or MgO
(b) LiF or LiBr
(c) Mg3N2 or NaCl
4. How many non-bonding lone pairs are on the underlined atoms in these compounds?
a) HBr
b) H2S
c) CH4
5. Compare single, double, and triple bonds in a molecule, and give an example of each. For
the same bonding atoms, how does the bond length change from single bond to triple bond?
6. Compare the bond strength of the following covalent bonds:
a) N―N & P-P
c) C≡C & Si―Si
b) O―O & O=O
7. Compare the properties of ionic compounds and covalent compounds.
8. How is electronegativity different then electron affinity?
(Adapted from Chemistry by Chang)
Attach Scratch paper as needed.
Ch. 9 Homework Questions
9. Describe in general how the electronegativities of the elements change according to position
in the periodic table.
10.What is a polar covalent bond?
11. List the following bonds in order of increasing ionic character: the lithium-to-fluorine bond
in LiF, the potassium-to-oxygen bond in K2O, the nitrogen-to-nitrogen bond in N2, the
sulfur-to-oxygen bond in SO2, the chlorine-to-fluorine bond in ClF3.
12. Classify the following bonds as ionic, polar covalent, or covalent:
(a) the C-C bond in H3C-CH3
(b) the KI bond in KI
(c) the C-F bond in CF4.
13. Write Lewis structures for the following molecules and ions:
(a) NCl3
(b) OCS
(c) H2O2
(d) C3H6
(e ) C2H7N
(f) OF2
(g) N2F2
(h) Si2H6
(i) OH-
(j) NH4+
(k) CH3N+H3
(Adapted from Chemistry by Chang)
(l) N2
(m) PH3
(n) HCN
Attach Scratch paper as needed.
(o) N2H4
Ch. 9 Homework Questions
14. Draw three resonance structures for the chlorate ion,ClO3- (Show formal charges).
15. a) Add all necessary formal charges for the Lewis structure of Nitrate.
b) What is Nitrate’s net charge?
16.Write Lewis structures for the following species and show formal charges:
(a) HCO2-
(b) CH2NO2-
Relative positions of the atoms are as follows:
(net -1 charge, but takes more than one formal charge)
17. Give 3 examples of compounds that do not satisfy the octet rule. Write a Lewis structure for
each.
(Adapted from Chemistry by Chang)
Attach Scratch paper as needed.