Transcript Atomic Radius

Ch. 5 - The Periodic Table
Atomic Radius (pm)
250
Periodic
Trends
200
150
100
50
0
0
5
10
Atomic Number
15
20
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
10
Atomic Number
15
20
B. Chemical Reactivity
Families
Similar valence e- within a group result
in similar chemical properties
1
2
3
4
5
6
7
B. Chemical Reactivity
1
2
3
4
5
6
7
Alkali Metals
Alkaline Earth Metals
Transition Metals
Halogens
Noble Gases
C. Other Properties
Atomic Radius
size of atom
Ionization Energy
© 1998 LOGAL
Energy required to remove one e- from a
neutral atom.
Melting/Boiling Point
© 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
15
20
D. Atomic Radius
Atomic Radius
Increases to the LEFT and DOWN
1
2
3
4
5
6
7
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
G. Ionic Radius
Ionic Radius
Cations (+)
lose esmaller
Anions (–)
gain e-
larger
© 2002 Prentice-Hall, Inc.
Atomic vs. Ionic Radii
Atomic radii trend
Tend to compare neutral atoms of
different elements
Ionic radii trend
Compare neutral atom against the ionic
form of the element.
E. Ionization Energy
1st Ionization Energy (kJ)
Ionization Energy
He
2500
Ne
2000
Ar
1500
1000
500
Li
Na
K
0
0
5
10
Atomic Number
15
20
E. Ionization Energy
Ionization Energy
Increases UP and to the RIGHT
1
2
3
4
5
6
7
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
e-
F. Melting/Boiling Point
Melting/Boiling Point
Highest in the middle of a period.
1
2
3
4
5
6
7
Electronegativity
The tendency of an atom to attract
electrons to form ionic bonds.
Electronegativity Trend
Increases up and to the right.
Examples
Which atom has the larger radius?
Be or Ba
Ba
Ca or Br
Ca
Examples
Which atom has the higher 1st I.E.?
N or Bi
N
Ba or Ne
Ne
Examples
Which atom has the higher
melting/boiling point?
Li or C
C
Cr or Kr
Cr
Examples
Which particle has the larger radius?
S or
2S
2S
Al or
3+
Al
Al