iiiiii periodic trends the periodic table. 1.atomic radius y½ the distance between two identical...
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I II III
Periodic Trends
The Periodic Table
0
50
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150
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0 5 10 15 20Atomic Number
Ato
mic
Ra
diu
s (
pm
)
1. Atomic Radius ½ the distance between
two identical atoms
bonded together
© 1998 LOGAL
2. Ionization Energy Energy required to
remove one e- from a
neutral atom.
© 1998 LOGAL
Periodic Properties
3. Electron Affinity Attraction for additional electrons
Periodic Properties
4. Electronegativity “Pull” an atom has on
electrons when bonded to another atom
1
2
3
4 5
6
7
Atomic Radius
1. Increases to the LEFT and DOWN
A. Atomic Radius
2. Why larger going down?
a) Adding energy levels
b) Shielding - core e- block the attraction between the nucleus and the valence e-
A. Atomic Radius
3. Why smaller to the right?
a) Increased nuclear charge (i.e. more protons in nucleus) without more shielding pulls e- in tighter
A. Atomic Radius
A. Atomic Radius
11 p+11 p+
NaNa
17 p+17 p+
ClCl
Nucleus Nucleus notnot strong enough to pull strong enough to pull
valence e- in tightvalence e- in tightStronger nucleus pulls Stronger nucleus pulls
valence e- in tightvalence e- in tight
Ionic Radius Cations (+)
lose e-
smaller
© 2002 Prentice-Hall, Inc.
Anions (–)
gain e-
larger
B. Ionic Radius
Ionic Radius “Tug of War” between positive nucleus and negative electrons.
Cations: nucleus is “stronger”
Anions: electrons are “stronger”
B. Ionic Radius
Which atom has the larger radius?
Be or Ba
Ca or Br
Ba
Ca
Examples
Which particle has the larger radius?
S or S2-
Al or Al3+
S2-
Al
Examples
First Ionization Energy – energy needed to remove ONE electron.
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0 5 10 15 20Atomic Number
1s
t Io
niz
ati
on
En
erg
y (k
J)
C. Ionization Energy
KNaLi
Ar
NeHe
1
2
3
4 5
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7
First Ionization Energy
1. Increases UP and to the RIGHT
C. Ionization Energy
2. Why opposite of atomic radius?
a) In small atoms, e- are close to the nucleus where the attraction is stronger; it takes a lot of energy to strip an e- away!
3. Why small jumps within each group?
a) Stable e- configurations don’t want to lose e-
C. Ionization Energy
Mg 1st I.E. 736 kJ
2nd I.E. 1,445 kJ
Core e- 3rd I.E. 7,730 kJ
4. Successive Ionization Energies
a) Large jump in I.E. occurs when a CORE e- is removed after all valence e- have been removed.
C. Ionization Energy
Al 1st I.E. 577 kJ
2nd I.E. 1,815 kJ
3rd I.E. 2,740 kJ
Core e- 4th I.E. 11,600 kJ
4. Successive Ionization Energies
a) Large jump in I.E. occurs when a CORE e- is removed after all valence e- have been removed.
C. Ionization Energy
Which atom has the higher 1st I.E.?
N or Bi
Ba or Ne
N
Ne
Examples
D. Electron Affinity
1
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3
4 5
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7
Electron Affinity
1. Increases UP and to the RIGHT
D. Electron Affinity
2. Why smaller going down?
a) e- further from the nucleus
b) Greater shielding; additional e- feel the attraction from the nucleus less.
3. Why greater to the right?
a) Higher nuclear charge without greater shielding; stronger nucleus has a greater attraction for e- (atoms tend to make anions)
Which atom has the higher e- affinity?
K or Br
F or I
Br
F
Examples
E. Electronegativity
1
2
3
4 5
6
7
Electronegativity
1. Increases UP and to the RIGHT
F
If the following atoms were bonded together, which would have the higher electronegativity?
P or S
Se or O
S
O
Examples
1
2
3
4 5
6
7
Melting/Boiling Point Highest in the middle of a period.
F. Melting/Boiling Point