Transcript pertrends_pres

Ch. 5 - The Periodic Table
Atomic Radius (pm)
250
III. Periodic
Trends
(p. 140 - 154)
200
150
100
50
0
0
5
10
Atomic Number
15
20
C. Johannesson
I
II
III
A. Periodic Law
When elements are arranged in order of
increasing atomic #, elements with similar
properties appear at regular intervals.
Atomic Radius (pm)
250
200
150
100
50
0
0
5
C.
10
Atomic
Number
Johannesson
15
20
B. Chemical Reactivity
Families
Similar valence e- within a group result
in similar chemical properties
1
2
3
4
5
6
7
C. Johannesson
B. Chemical Reactivity
1
2
3
4
5
6
7
Alkali Metals
Alkaline Earth Metals
Transition Metals
Halogens
Noble Gases
C. Johannesson
C. Other Properties
Atomic Radius
size of atom
First Ionization Energy
© 1998 LOGAL
Energy required to remove one e- from a
neutral atom.
Melting/Boiling Point
C. Johannesson
© 1998 LOGAL
D. Atomic Radius
Atomic Radius
K
Atomic Radius (pm)
250
Na
200
Li
150
100
Ar
Ne
50
0
0
5
10
Atomic Number
C. Johannesson
15
20
D. Atomic Radius
Atomic Radius
Increases to the LEFT and DOWN
1
2
3
4
5
6
7
C. Johannesson
D. Atomic Radius
Why larger going down?
Higher energy levels have larger orbitals
Shielding - core e- block the attraction
between the nucleus and the valence e-
Why smaller to the right?
Increased nuclear charge without additional
shielding pulls e- in tighter
C. Johannesson
E. Ionization Energy
1st Ionization Energy (kJ)
First Ionization Energy
He
2500
Ne
2000
Ar
1500
1000
500
Li
Na
K
0
0
5
10
Atomic Number
C. Johannesson
15
20
E. Ionization Energy
First Ionization Energy
Increases UP and to the RIGHT
1
2
3
4
5
6
7
C. Johannesson
E. Ionization Energy
Why opposite of atomic radius?
In small atoms, e- are close to the nucleus
where the attraction is stronger
Why small jumps within each group?
Stable e- configurations don’t want to lose
eC. Johannesson
E. Ionization Energy
Successive Ionization Energies
Large jump in I.E. occurs when a CORE
e- is removed.
Mg
Core e-
1st I.E.
736 kJ
2nd I.E.
1,445 kJ
3rd I.E.
7,730 kJ
C. Johannesson
E. Ionization Energy
Successive Ionization Energies
Large jump in I.E. occurs when a
CORE e- is removed.
Al
Core e-
1st I.E.
577 kJ
2nd I.E.
1,815 kJ
3rd I.E.
2,740 kJ
4th
I.E.
C. Johannesson
11,600 kJ
F. Melting/Boiling Point
Melting/Boiling Point
Highest in the middle of a period.
1
2
3
4
5
6
7
C. Johannesson
C. Johannesson
G. Ionic Radius
Ionic Radius
Cations (+)
lose esmaller
Anions (–)
gain e-
larger
C. Johannesson
© 2002 Prentice-Hall, Inc.
C. Johannesson
Ionic Radius
Increases right to left
- atoms lose e-; they become smaller
because they may drop energy level or
because outer shell has less electrons so
less attraction to nucleus
Increases top to bottom
-higher energy level means that valence
electrons are further away so increase in
size.
C. Johannesson
C. Johannesson
Examples
Which atom has the larger radius?
Beor Ba
Ba
Caor Br
Ca
C. Johannesson
Examples
Which atom has the higher 1st I.E.?
N or Bi
N
Baor Ne
Ne
C. Johannesson
Electronegativity
Ability to attract electrons in a bond
*doesn’t apply to Noble gases- Why?
Related to ionization energy.
-low electronegativity is because the nuclei
don’t exert a strong attractive force
-Group- as atmoic # increases- increased
distance between valence e- and nucleus.
**SO: decreases down group, decreases
right to left across period.
C. Johannesson
C. Johannesson
Examples
Which atom has the higher
melting/boiling point?
Li or C
C
Cr or Kr
Cr
C. Johannesson
Examples
Which particle has the larger radius?
S or
2S
2S
Al or
3+
Al
Al
C. Johannesson