1. III. Periodic Trends (p. 140 - 154)
Ch. 5 - The Periodic Table
III. Periodic Trends (p )

2. A. Periodic Law
When elements are arranged in order of increasing atomic #, elements with similar properties appear at regular intervals.

3. B. Chemical Reactivity Families
Similar valence e- within a group result in similar chemical properties

4. B. Chemical Reactivity Alkali Metals Alkaline Earth Metals
Transition Metals
Halogens
Noble Gases

5. C. Other Properties Atomic Radius size of atom: ½ distance
between nuclei of identical
atoms bonded tog.
© 1998 LOGAL
First Ionization Energy
Energy required to remove one e- from a neutral atom.
© 1998 LOGAL

6. D. Atomic Radius
Atomic Radius K Na Li Ar Ne

7. D. Atomic Radius
Atomic Radius
Increases to the LEFT and DOWN

8. 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

9. E. Ionization Energy ion: atom or group of atoms with a (+) or (-)
First Ionization Energy He Ne
ion: atom or
group of atoms
with a (+) or (-)
charge Ar Na Li K
ionization: any process that results in the
formation of an ion

10. E. Ionization Energy First Ionization Energy
Increases UP and to the RIGHT

11. 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-

12. E. Ionization Energy Successive Ionization Energies
Large jump in I.E. occurs when a CORE e- is removed.
Mg 1st I.E kJ
2nd I.E. 1,445 kJ
Core e- 3rd I.E. 7,730 kJ

13. E. Ionization Energy Successive Ionization Energies
Large jump in I.E. occurs when a CORE e- is removed.
Al 1st I.E kJ
2nd I.E. 1,815 kJ
3rd I.E. 2,740 kJ
Core e- 4th I.E. 11,600 kJ
EXPLAIN WHY MORE ENERGY IS REQUIRED TO REMOVE E- FROM AN ION THAN A NEUTRAL ATOM IN TERMS OF SHIELDING

14. F. Melting/Boiling Point
Highest in the middle of a period.

15. G. Ionic Radius Ionic Radius Cations (+) lose e- smaller Anions (–)
gain e-
larger
© 2002 Prentice-Hall, Inc.

16. Energy released: negative value Energy gained: positive value
H. ELECTRON AFFINITY
electron affinity: (def) energy change that occurs when an electron is acquired by a neutral atom
A + e-  A- + energy
Energy released: negative value
Energy gained: positive value

17. H. ELECTRON AFFINITY Trends:
Among elements of each period, the halogens gain electrons most readily.
(analogy of buying & selling)
As a general rule, electrons are added with more difficulty down a group.

18. H. ELECTRON AFFINITY
Adding Electrons to Negative Ions
It is always more difficult to add a 2nd electron to an already charged ion.
This makes all 2nd electron affinity values positive.

19. I. ELECTRONEGATIVITY Down a group, tend to decrease or stay the same
electronegativity: (def) a measure of the ability of an atom in a chemical compound (bonding) to attract electrons
TRENDS:
Across a period, tend to increase
Down a group, tend to decrease or stay the same

20. J. VALENCE ELECTRONS
valence electrons: (def) electrons available to be lost, gained, or shared in the formation of chemical compounds

21. S or S2- Al or Al3+ S2- Al Examples
Which particle has the larger radius?
S or S2-
Al or Al3+
S2- Al

22. Examples
Which atom has the higher 1st I.E.?
N or Bi
Ba or Ne N Ne

23. Examples
Which atom has the larger radius?
Be or Ba
Ca or Br Ba Ca

24. Li or C Cr or Kr C Cr Examples
Which atom has the higher melting/boiling point?
Li or C
Cr or Kr C Cr

25. REVIEW QUESTION Which of the following is the most reactive metal?
Neon, Boron, Beryllium, Lithium, Silicon
Lithium

26. REVIEW QUESTION Sodium, chlorine, magnesium, argon
The element in period 3 with the largest atomic radius is:
Sodium, chlorine, magnesium, argon
Sodium

27. REVIEW QUESTION Phosphorus, Carbon, Chlorine, Boron, Iodine
Which of the following elements is most electronegative?
Phosphorus, Carbon, Chlorine, Boron, Iodine
Chlorine

28. REVIEW QUESTIONS Fluorine, chlorine, Bromine, Iodine
Which of the following has the most metallic character?
Fluorine, chlorine, Bromine, Iodine
Iodine

29. REVIEW QUESTIONS
Which ionization energy (1st, 2nd, 3rd, etc) will show a jump in value for an atom of Be?
3rd ionization energy

30. REVIEW QUESTIONS F – most negative values (will spend the most money)
Which electron affinity value will be more negative: for F or N?
F – most negative values (will spend the most money)
All second electron affinity values are: positive or negative?
positive