1. Chemical Periodicity? What?

2. Periodicity When elements are organized in order of  atomic mass, and
grouped by similarities of chemical properties,
a certain “pattern” or periodicity
of properties becomes evident
Draft for first version of
Mendeleev's periodic table
(17 February 1869).

3. Review of the Periodic Table

4. Review of the Periodic Table
Group IA – alkali metals
Review of the Periodic Table

5. Group IA – alkali metals
H s1
Li s22s1
Na11 - 1s22s22p63s1
K s22s22p63s23p64s1
Rb37 - 1s22s22p63s23p63d104s24p65s1
Cs55 - 1s22s22p63s23p63d104s24p64d105s25p66s1
Fr s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p67s1

6. Review of the Periodic Table
Group IIA – alkaline earth metals
Review of the Periodic Table

7. Group IIA – alkaline earth metals
Be s2 2s2
Mg12 - 1s22s22p63s2
Ca20 - 1s22s22p63s23p64s2
Rb38 - 1s22s22p63s23p63d104s24p65s2
Cs55 - 1s22s22p63s23p63d104s24p64d105s25p66s2
Fr s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p67s2

8. Review of the Periodic Table
Group VIII – Noble Gases
Review of the Periodic Table

9. Group VIII – Noble Gases
He s2
Ne10 - 1s22s22p6
Ar18 - 1s22s22p63s23p6
Kr36 - 1s22s22p63s23p63d104s24p6
Cs54 - 1s22s22p63s23p63d104s24p64d105s25p6
Rn s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p6

10. Review of the Periodic Table
Group VII – Halogens
Review of the Periodic Table

11. Group VII – Halogens F9 - 1s22s22p5 Cl17 - 1s22s22p63s23p5
Br35 - 1s22s22p63s23p63d104s24p5
I s22s22p63s23p63d104s24p64d105s25p5
At85 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p5

12. Review of the Periodic Table
Group VI

13. Group VI
O8 - 1s22s22p4
S16 - 1s22s22p63s23p4
Se34 - 1s22s22p63s23p63d104s24p4
Te52 - 1s22s22p63s23p63d104s24p64d105s25p4
Po84 - 1s22s22p63s23p63d104s24p64d104f145s25p65 d106s26p4

14. Electron’s Role in Chemical Behavior
Atoms are most stable when their outermost “s” and “p” subshells are filled. – “the rule of 8”
Electron’s in the outermost shell determine chemical reactivity

15. Periodic Table and e- config.1 2 3 4 5 6 7
Increasing energy level (shell)
px1 py1 pz1 px2 py2 pz2
s1 s2
Increasing energy sublevel (subshell)

16. Periodic Patterns - Atomic Radii

17. Atomic Radii

18. Periodicity and Atomic Radius
In group:
atomic radius increases as you move down the column
Across period:
Atomic radius decreases as you
Move from left to right
Rationale:
group – adding outermost electron shell
row –  pulling in with  nuclear charge

19. Ionic Radius
97pm vs pm
190pm vs pm

20. Periodic Patterns and Ionic Radius
In group:
ionic radius increases as you move down the column
Across period:
Ionic radius is max in group 5
Lower on left and right
Rationale:
group –outermost shell
row – transition between losing and gaining electrons to reach stability

21. Ionic Radius

22. Periodic Patterns and Ionization Energy
Ionization energy ≡ energy needed to remove an electron from an atom or ion
first ionization energy - energy needed to remove an electron from a neutral atom
second ionization energy - energy needed to remove a second electron from a positively charged ion

23. Ionization Energy

24. Periodic Patterns and Ionization Energy
In group:
ionization energy  as you move down the column
Across period:
Ionization energy  as you move from left to right
Rationale:
group –outermost shell electrons
farther away from nucleus
row – outermost electron more tightly
held

25. Ionization Energy

26. Periodicity and Electronegativity
Electronegativity ≡ a measure of how tightly held an electron is.

27. Electronegativity

28. Periodicity and Electronegativity
In group:
electronegativity  as you move down the column
Across period:
Electronegativity  as you move from left to right
Rationale:
group –atoms more willing to accept another electrons due to  nuclear charge and shielding
row – atoms move closer to completed “s” and “p” orbitals and stability

29. Electronegativity

30. Periodic Trends – Summary
Decreasing Atomic Radii
Decreasing Ionic Size
Increasing Ionization Energy
Increasing Electronegativity
Decreasing Ionization Energy
Decreasing Electronegativity
Increasing Atomic Radii
Increasing Ionic Radius