I II III

Periodic Trends

The Periodic Table

0

50

100

150

200

250

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.

0

500

1000

1500

2000

2500

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

6

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

2

3

4 5

6

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