REVIEW: Chapter 8 - Covalent Bonding
1. Typically, how many bonds & lone pairs will each have when covalently bonding?
a. Boron – 3 bonds; 0 lone pairs
d. Iodine – 1 bond; 3 lone pairs
b. Silicone – 4 bonds; 0 lone pairs
e. Nitrogen – 3 bonds; 1 lone pair
c. Neon – 0 bonds; 4 lone pairs
f. Oxygen – 2 bonds; 2 lone pairs
2. Which elements do not follow the octet rule? (Hint – there are four we went over)
a. __H__ & __B__ never follow the octet rule.
b. __P__ & __S__ sometimes don’t follow the octet rule.
3. What type of bond will each combination of atoms form?
a. F & N – 2 nonmetals, therefore covalent
d. B & Cl – 2 nonmetals, therefore covalent
b. Al & O – 1 metal/1 nonm., therefore ionic
e. Ca & I – 1 metal/1 nonm., therefore ionic
c. Na & S – 1 metal/1 nonm., therefore ionic
f. Fe & Cu – 2 metals, therefore metallic
4. What is the difference between:
a. Molecules & Compounds?
Compounds can be made using all types of bonds (ionic, covalent or metallic), but molecules can
only be made using covalent bonds
b. Monatomic elements & Diatomic molecules ?
Monatomic elements exist as single atoms; diatomic molecules are made up of two of the same
atom
c. Structural formulas, Empirical formulas, & Molecular formulas?
All three are for covalent bonds only! Molecular show the actual number of atoms in the molecule;
Empirical give the lowest whole number ratio; Sturctural formulas are not really formulas, they are
drawing of the molecule.
d. Polar bonds & Non-polar bonds?
Both describe covalent bonds! In a polar bond the electrons are NOT shared equally; in a non-polar
bond electrons are shared equally
5. Classify each of the following as an atom or a molecule:
a. Be, atom
b. CO, molec.
c. N2, molec.
d. H2O,molec.
e. Ne, atom
6. How many diatomic elements are there? __7__
List the diatomic elements: Br, I, N, Cl, H, O, F
7. How many monatomic elements are there? __6__
List them: He, Ne, Ar, Kr, Xe, Rn
8. Complete the table with differences between ionic & covalent compounds:
Covalent
Ionic
Non-metals
Metal & non-metal
Bond strength…
weaker
stronger
Melting point…
Lower
Higher
Gas or liquid
Solid
Shared
Gained/lost
Type of element…
State @ room temp…
Electrons are…
9. Draw the structure of each covalent molecules. They may contain single, double, or triple bonds:
See drawing posted in classroom
10. Would a bond between the following elements be polar or non-polar?
a. C & I – non-polar, because they have the same electronegativity & they will share electrons equally
b. Si & N – polar, b/c they have diff. electronegatity & nitrogen will ‘hog’ the electrons they are sharing
c. H & H – non-polar, b/c they’re the same atom & have the same electronegatity & will share e- equally
11. Draw each molecules; label the dipoles, if any; identify each molecule as polar or non-polar
a. PH3 – polar b/c bonds are not all opposite eachother (the lone pair on P is throwing it off)
b. CF4 - nonpolar b/c all the bonds are equal and opposite of each other
c. SiHF3 – polar b/c the bonds are not all equal (3 are to F, but 1 is to H)
d. N2 – nonpolar b/c all the same atom, therefore they share the e- equally
e. ClCN – nonpolar, b/c the atoms are different but Cl & N have the same electronegativity,
therefore they are equal and opposite each other
12. Write formulas for the following covalent compounds:
a. hexaboron nonasilicide – B6Si9
b. chlorine dioxide – ClO2
c. hydrogen diiodide – HI2
d. triIodine octafluoride – I3F8
e. dicarbon monosulfide – C2S
f. dinitrogen heptoxide – N2O7
13. Write the names for the following covalent compounds:
a. P4S5 – tetraphosphorous pentasulfide
b. SeF6 – selenium hexaflouride
c. B2Si7 – diboron heptasilicide
d. NF7 – nitrogen heptaflouride
e. S3O9 – trisulfur nonaoxide
f. Si4O8 – tetrasilicon octaoxide
14. Complete the table:
Nitrogen Trihydride
Dicarbon Dihydride
Molecular Formula
NH3
C2H2
Empirical Formula
NH3
CH
Structural Formula
Drawing should be:
Nitrogen has 1 lone pair, and a
single bond to each hydrogen
H–C=C–H
# Lone Pairs in molecule
1 (on Nitrogen)
0