CP Chemistry
Unit 3 Review
Concepts:
• Periodic law
• Metals, nonmetals,
metalloids/semimetals
• Periods
• Groups
• Periodic trends
o Electron shielding effect
o Effective nuclear charge
o Coulomb’s law
o Atomic radius
o Ionic radius
o Ionization energy
 Successive ionization
energy
o Electronegativity
• Chemical bond
• Octet rule and exceptions
• Types of chemical bonds
o Ionic
o Covalent (polar and nonpolar)
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o Metallic
Lewis structures
Polyatomic ions
Properties of ionic compounds,
covalent compounds, and metals.
Naming compounds
o Type I, II, and III
Shapes of molecules
o VSEPR
o Bond angle
Polarity
o Dipole arrow
o Net dipole moment
o Polar molecules
Intermolecular forces (Van der Waals
forces)
o London dispersion
o Dipole-dipole
o Hydrogen bonding
Practice Problems:
1. How does the atomic radius change from left to right across a period. Why?
2. How does the atomic radius change from top to bottom for a group. Why?
3. How does the ionization energy change from left to right across a period. Why?
4. How does the ionization energy change from top to bottom for a group. Why?
5. Why do large atoms have small ionization energies?
6. Why are metal ions smaller than their metal atoms?
7. Why are nonmetal ions larger than their nonmetal atom?
8. Why does F have a higher electronegativity than Li? Be specific?
9. What electron configuration has the greatest stability?
10.Order the following groups from smallest to largest radii.
a) I, Ba, Cs, Xe
Xe, I, Ba, Cs
b) Kr, Br, Sr, Se
Kr, Br, Se, Sr
c) Li, K, Fr, Cs
Li, K, Cs, Fr
11. Order the following groups from highest to lowest ionization energy.
a) Na, Mg, Ca
Mg, Na, Ca
b) Br, F, Se
F, Br, Se
c) K, Sr, Ba
*Sorry, this one is impossible without data. Sr, Ba, K
12. Describe effective nuclear charge (Zeff).
13.Calculate the Zeff for Ca and Br. Can Zeff be used to explain atomic radius trends?
Explain.
Ca: Zeff=20-18 =2
Br: Zeff = 35-18 = 7
Yes-bromium has a smaller radius than calcium because of greater effective nuclear
charge.
14.What is ionization energy?
15.Why is the 3rd ionization energy of Mg so much larger than it’s 2nd IE?
The 3rd IE for Mg is the energy required to remove the third e- from the atom which
would be a core e- that is closer to the nucleus.
16.Why is the ionization energy for Al less than Mg?
The ionization for Al is less because the ionized e- is being removed from a “p” sublevel
with only one e-, the “p” sublevel is slightly farther from the nucleus than the “s”, therefore
requiring less energy. Also, removing the 1 e- in the P sublevel results in a configuration
ending in a full “s” sublevel.
17.The ionization energies for element X are listed in the table below. On the basis of
the data, element X is most likely
Ionization Energies for element X (kJ mol-1)
First
Second
Third
Fourth
Fifth
580
1,815
2,740
11,600
14,800
(A) Na
(B) Mg
(C)
Al
(D)
Si
18. Which property generally decreases across the periodic table from sodium to
chlorine?
(A) 1st ionization energy
(B) Atomic mass
(C) Ionic radius
(D) Atomic radius
19. Where are metals, nonmetals, and metalloids found on the periodic table? Name one
example of each.
20.Why do bonds form? What forces are involved in bonding?
21.Compare and contrast ionic bonding and covalent bonding.
22.What circumstance must exist for a bond to be nonpolar covalent?
23.When atoms of a metal react with atoms of a nonmetal, what type of electron
configurations do the resulting ions attain?
24.What are 3 properties of ionic compounds?
25.What are 3 properties of polar/nonpolar molecules?
26.Explain the difference between single, double, and triple bonds. Which is strongest?
27. Explain the difference between a covalent bond formed between two atoms of the
same element and a covalent bond formed between atoms of two different
elements?
28.What is the “glue” or force that holds compounds (ionic) together. How is that
different from the “glue” that holds molecules (covalent) together?
29.What is lattice energy?
30.What two factors affect lattice energy?
31.What is a crystal lattice?
32.For each of the following sets of elements, identify which element would be expected
to be most electronegative and which would be expected to be least electronegative.
a) K, Sc, Ca
least K, Ca, Sc most
b) Br, F, At
least At, Br, F most
c) C, O, N
least C, N, O most
33.On the basis of the electronegativity values, indicate whether each of the following
bonds would be expected to be ionic, nonpolar covalent, polar covalent, or metallic.
a) H-F ionic (but actually polar)
c) Cl-F polar
e) Cu-Zn metallic
b) Na-F ionic d) Ca-F ionic
f) Fe-Fe metallic
34. On the basis of electronegativity values, indicate which is the more polar bond in
each of the following pairs.
a) H-N or H-P
c) H-P or H-S
b) H-O or H-S
d) H-S or H-I (same)
35.In each of the following molecules, which end of the molecule is negative relative to
the other end? Use dipole arrows.
a) HCl
Cl
c) BrF
F
b) CO
O
d) HF
F
36. Arrange the following ionic compounds in order of increasing melting point: LiCl,
LiF, MgCl2, Al2S3
Low melting point LiCl, LiF, MgCl2, Al2S3
High melting point
37.Give the name or write the formula for the following:
N 2O
___dinitrogen monoxide___
Cr(NO2)2
___chromium (II) nitrite__
V 2O 5
___vanadium (IV) oxide_
(NH4)2Cr2O7
___ammonium dichromate_
ZnC2O4
___ zinc (II) oxalate ____
Al(MnO4)3
____Aluminum permanganate_____
38.Explain why CO2 and CCl4 are both nonpolar even though they contain polar bonds?
Dipole arrows are geometrically symmetrical (they cancel out)
39.Explain why BF3 is trigonal planar, yet NH3 is trigonal pyramid
NH3 has a lone pair on the nitrogen, making the domain geometry tetrahedral.
40.Why is the bond angle for H2O less than 109.5°, yet for SO2 slightly less than 120°?
For H2O, there are 4 electron domains around oxygen making the domain geometry
tetrahedral. The two lone pairs squeeze the bond angle. SO2 only has 3 electron domains,
making the domain geometry a trigonal planar. The one lone pair squeezes the bond angle.
41.Identify the intermolecular force of attraction for the following molecules: skip
a) CO2
b) HF
c) CH4
42. Arrange these ionic compounds in order of increasing magnitude of lattice energy:
CaO, KBr, KCl, SrO.
Least lattice energy KBr, KCl, SrO, CaO Most lattice energy
43.Rank the following molecules from least polar to most polar: NH3, H2O, C2H6, HCl,
SO2
Least polar C2H6, (NH3 HCl about the same) H2O Most polar
44.Rank the following molecules in order of increasing boiling point: Skip