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Review Chemistry I Unit 6: Covalent Bonding and Nomenclature
1. Why do atoms share electrons in covalent bonds with other atoms rather than
remaining as single atoms?
To acquire a more stable electron configuration (8 valence electrons)
2. A molecule is a neutral group of atoms held together by ______ .
A.
B.
C.
D.
ionic bonds
unshared electrons
partial charges
covalent bonds
3. Compounds formed by covalent bonds usually contain _______________.
A.
B.
C.
D.
halogens and oxygen
two or more nonmetals
a metal and a nonmetal
positive and negative ions
4. Which of the following is a covalent compound?
A.
B.
C.
D.
Na2O
AlCl3
SCl6
CuO
5. How do atoms form covalent double bonds?
A.
B.
C.
D.
C
C
One atom loses two electrons to the other atom in the bond.
Two atoms share two pairs of electrons.
Two atoms share two single electrons.
Two atoms share one electron.
6. Which of these elements does NOT exist as a diatomic molecule?
A.
B.
C.
D.
P
Cl
O
N
?
?
1
7. A bond formed between a carbon atom and hydrogen atom is likely to be ____.
A.
B.
C.
D.
polar covalent
dipolar
ionic
nonpolar covalent
8. Which of the following bonds is the most polar (i.e. has the greatest difference in electronegativity)?
A.
B.
C.
D.
C—C
H—N
O—H
H—F
9. Which of the following covalent bonds is the least polar?
A.
B.
C.
D.
H—Cl
H—C
Cl—Cl
H—N
10. Which is TRUE of a nonpolar covalent bond?
A.
B.
C.
D.
electrons are shared unequally between atoms
a cation is bonded to an anion
electrons are transferred between atoms
electrons are shared equally between atoms
11. Draw the Lewis dot structure for CO2 :
Does CO2 contain polar bonds? ___yes
Is CO2 a polar molecule? __no_
If so, how many? __2_
If not, explain why not. __the polar bonds
are symmetrically arranged and cancel each other out.__
12. The following molecules contain polar bonds. Which is the only nonpolar molecule?
A.
B.
C.
D.
HCl
NH3
H2O
CBr4
(hint: drawing the Lewis structures can help)
2
water molecule
water molecule
13. Water molecules are polar because they have _______polar bonds___________
that are arranged __asymmetrically in a bent shape___________.
14. Describe properties that are common in typical molecular compounds.
conductor:
good or poor
melting point: high
or
low
boiling point: high
or
low
net charge:
neutral or charged
#15-20 Write the NAME or FORMULA for the following molecular compounds:
15. CS2
____carbon disulfide________
16. CCI4
____carbon tetrachloride______
17. S2O6
___disulfur hexoxide______
18. triboron monoxide
__B3O__
19. tetraphosphorus pentoxide
__P4O5__
20. arsenic trihydride
_AsH3__
21. In drawing a Lewis structure, what is special about hydrogen (H) ?
A.
B.
C.
D.
It achieves an octet of 8 electrons.
It can form up to four bonds with 8 shared electrons.
It can only form one double bond.
It can only form one single bond with no unshared electrons around it.
3
For #22-27:
-Draw the Lewis dot structures for the following compounds.
-Identify the shape of the molecule as one of these 5: linear, bent, trigonal planar,
trigonal pyramidal, tetrahedral
-Identify the molecule as polar or nonpolar by circling the correct label.
22. HBr
shape:
polar
or
nonpolar
polar
or
nonpolar
polar
or
nonpolar
polar
or
nonpolar
polar
or
nonpolar
polar
or
nonpolar
linear
23. NI3
shape:
trigonal pyramidal
24. N2
shape:
linear
25. Cl2
shape:
linear
26. SO2
shape:
bent
27. CH2F2
shape:
tetrahedral
4