Download Chemistry FIFTH EDITION by Steven S. Zumdahl University of Illinois

Chemistry
FIFTH EDITION
by Steven S. Zumdahl
University of Illinois
Copyright©2000 by Houghton
Mifflin Company. All rights reserved.
1
Chemistry
FIFTH EDITION
Chapter 7
Atomic Structure and
Periodicity
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2
Section 7.12
Periodic Trends in Atomic Properties
• Ionization Energy
• Electron Affinity
• Atomic size
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3
Ionization Energy
•
The quantity of energy required
to remove an electron from the
gaseous atom or ion.
X (g)  X+ (g) + eCopyright©2000 by Houghton
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4
Consider step-ionization:
Al (g)  Al+ (g) + e-
I1 = 580 kJ/mole
Al+ (g)  Al2+ (g) + e- I2 = 1815 kJ/mole
Al2+ (g)  Al3+ (g) + e- I3 = 2740 kJ/mole
Al3+ (g)  Al4+ (g) + e- I4 = 11600 kJ/mole
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5
• 2nd IE larger than 1st.
•Largest jump after removing Ve-.
•See Table 7.5 page 328.
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6
Figure 7.31
The Values of First Ionization Energy for the Elements in the First Six Periods
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7
Periodic Trends
•
•
First ionization energy:
increases from left to right
across a period;
•
decreases going down a group.
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8
Figure 7.32
Trends in Ionization Energies for the Representative Elements
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9
Let’s Read!!!
• Page 329 – 330.
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10
Electron Affinity
•
The energy change associated with
the addition of an electron to a
gaseous atom.
• X(g) + e  X(g)
If addition of an electron is exothermic,
then EA is negative.
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11
EA generally becomes more negative
from L  R across a period.
EA becomes more positive as you go
down a group.
There are numerous EXCEPTIONS!
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12
Figure 7.33
The Electronic Affinity Values for Atoms Among the
First 20 Elements that Form Stable, Isolated X- Ions
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13
Atomic Radius
• Just as size of orbital can’t be exactly
specified,
Size of an atom can’t be exactly specified.
1) Covalent Atomic radii
2) Metallic Radii
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14
Figure 7.34
The Radius of an Atom
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15
Figure 7.35
Atomic Radii for
Selected Atoms
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16
Section 7.13
Information Contained in the Periodic Table
• Grps. of Representative elements exhibit
similar chemical properties that change in
a regular way.
• Each group has the same valence electron
configuration.
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17
It is the number and type of
valence electrons that primarily
determine an atoms chemistry.
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18
Information Contained in the
Periodic Table
•
Certain groups have special names
(alkali metals, halogens, etc).
•
Metals and nonmetals are characterized
by their chemical and physical properties.
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19
Figure 7.36
Special Names for
Groups in the
Periodic Table
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Metals:
Tend to give up electrons
Form positive ions
Low ionization energy
Non-metals:
Tend to gain electrons
Form negative ions
Large ionization energy
Large negative electron affinity
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21
Metalloids
• Properties of both metals
and non-metals
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22
The Alkali Metals
• Read pages 335 – 338.
• Write a detailed summary of this section.
• Include properties & common reactions.
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23