Study Guide for Ch.8.1, 8.2, and Lewis Structures –
Covalent Compounds
1) What type of element make up most covalent compounds?
Nonmetals!!!
2) How many electrons must be shared between two atoms to make a
a) single bond __2__
b) double bond _4__
c) triple bond __6__
3) Name the seven elements that form diatomic molecules.
H2, N2, Cl2, I2, Br2, F2, O2
4) Name the following covalent compounds:
a) PH3 phosphorus trihydride
b) P2O5 diphosphorus pentoxide
c) CS2 carbon disulfide
d) CCl4 carbon tetrachloride
5) Identify the sigma and pi bonds in each of the following cmpds.:
a) O = C = O
This compound has a sigma and a pi for each double bond
b) H – C = C – H This compound has sigma bonds for the single bonds and a
sigman with two pi bonds for the triple bond
6) How do sigma bonds form?
Sigma bonds form by the head to head overlap of two s-orbitals, or by an
s-orbital and p-orbital, or by two p-orbitals. The overlap occurs between the
nuclei.
7) How do pi bonds form?
Pi bonds form by the side by side overlap of two parallel p-orbitals.
The overlap occurs both above and below the line connecting the two
nuclei
8) Answer with single bond, double bond or triple bond for each question:
a) longest bond – single bond
b) strongest bond- triple bond
c) shortest bond- triple bond
d) most electrons – triple bond
9) Define the following terms:
a)Exothermic: A reaction or process in which energy is given off.
b) Endothermic: A reaction or process in which energy is absorbed or
put into the process.
c) Bond Dissociation Energy: the energy required to break the bonds of
a covalent compound. This is almost
always positive in value because the
breaking covalent bonds usually involves
adding energy into the process
10) Name the following covalent compounds and acids:
a) NO nitrogen monoxide
b) As2O3 diarsenic trioxide
c) OF2 oxygen di fluoride
d) HNO2 nitrous acid
e) HCl hydrochloric acid
e) H2SO4 sulfuric acid
11) Write the formula for each of the following covalent compounds & acids:
a) hydrosulfuric acid
c) dinitrogen pentoxide
H2S
N2O5
b) chloric acid HClO3
d) chlorous acid HClO2
12) Fill in the blanks:
Bond dissociation energy is the energy required to break a covalent
bond. Since energy is added in order to break the bond then this is an
endothermic reaction and the value for the bond dissociation energy
will always be positive.
Most explosives are made with nitrogen based compounds and are
high in energy and very unstable. Examples of some
nitrogen based explosives are TNT, nitroglycerine,
and dynamite. The products of an explosion with nitrogen
based explosives will be low in energy and very stable.
Explosions release energy and thus are exothermic reactions.
13) Draw Lewis Structures for the following covalent compounds;
a) NH3
b) NH4+1+
c) NO31-
d) SO2