MATL 260/360
HOMEWORK #1
1. Table salt (NaCl) exhibits predominantly ionic bonding. The Na+ and Cl- ions have
electron structures that are identical to which two inert gases?
Na+ loses an electron, so it is identical to Ne. Whereas, Cl- gains an electron, so Ar.
2. Write the electron configurations for the following ions: Fe2+, and O2- .
Fe2+ => 1s22s22p63s23p63d6 O2- => 1s22s22p6
3. For a Na+-Cl- ion pair, attractive and repulsive energies EA and ER are
EA = -1.436/r and ER = 7.32(10)-6/r8
(a) Plot En, EA and ER on a single plot from r=0 to r=1.0 nm. Use a graphing
program such as Excel or Origin. Each student must generate and print their own
graph. sharing of graphs will result in a zero score for the entire homework #1.
(b) From this plot, determine ro (the equilibrium spacing) between Na+ and Cl-.
R = 0.18
(c) From this plot, determine the bond energy between Na+ and Cl-.
-5.3
(d) Mathematically determine ro and compare this with your answer in (b).
(7.32(10)-6)/r8 = 1.436/r => r = 1.754
4. What type(s) of bonding would be expected for each of the following materials:

brass (a copper-zinc alloy), Metallic

liquid Cl2, Covalent Bonding

barium sulfide (BaS), Ionic Bonding

solid xenon, Vander waals bonding

polypropylene covalent w/ vander walls bonding
5. Compute the percentage ionic character for GaP and MgO. (Note: Consult equation
in book).
%IC = (1-e-.25(X1-X2)^2) x100 => Xgap = 2.1-1.6 = 0.5 AND XMgo = 3.5-1.2 = 2.3
=> %IC = 55.5%
6. What is the main difference between chemical and physical bonding?
Chemical bonding changes the e- configuration while physical bonding does not.
7. List the three types of chemical bonds in the following order: from having more
restrictions to having less restrictions. List what those restrictions (and lack of
restrictions) are for each one of them.
1. Covalent Bonds:
Restrictions – Directional, bonding only besides specific atoms, more difficult
to form crystals, and complex structures.
Lack of Restrictions – more open structures
2. Ionic Bonds:
Restrictions – must be opposite charges to bond, different size of ions
Lack of Restrictions – non-directional, stoichiometry
3. Metallic bonds
Restrictions – only uses metallic ions
Lack of Restrictions – non-directional, easy to find structure that minimizes
energy, easier to form crystalline structures