1. Electron Configuration and Periodic Properties/Trends
Chapter 5
Section 3
Pgs

2. There is a correlation between the arrangement of elements in the periodic table and their electron configuration

3. This P.T. is color coded by main energy level…

4. Concepts to know about…
Atomic radius
Ionization energy
Electronegativity
Valence electron
Be able to compare periodic trends of main group elements and explain why these trends occur
“Main” group elements do not include the transition metals or rare Earth metals.

5. Atomic Radius…
One half of the distance between two nuclei of the identical atoms that are bonded together

6. Atomic radius trends… Across Periods… Down Groups/Families...
Smaller atoms across a period (left to right)
Caused by increasing positive charge of the nucleus pulling in the electrons
Down Groups/Families...
Atoms increase in size down a group/family
because higher main energy levels are being filled as you down a group

9. Ions...
Ions are… A single atom or a group of bonded atoms that have an overall positive or negative charge
Na+ Cl- Cr3+
Polyatomic ions: OH- CO CN-
Ionization is any process that results in the formation of an ion
How do ions form???
Loss or gain of electrons!!!

10. Ions... Cation = positive ion = electrons have been removed
Anion = negative ion = electrons have been added

11. Ionization energy...
Energy needed to remove one electron from a neutral atom is the first ionization energy ( symbolized as IE1 )
Second ionization energy, third ionization energy remove electrons from an ion too.
Second ionization energy is always larger than first. Third larger than second…

12. Ionization energy trends…
Across Periods…
Ionization energy increases across a period due to increases nuclear charge (# of protons w/in nucleus)
If electrons are closer to the nucleus they are harder to remove away...
Down Groups
Decreases down a group because the higher main energy levels are further from nucleus
Electrons that are farther away from nucleus can be removed more easily...

13. Ionization energy Trends

14. Valence Electrons…
Valence Electrons are available to be lost, gained or shared when forming chemical compounds
Valence electrons are the electrons found in the outermost S and P orbitals only!!
there are always a maximum of 8 v.e. (S holds 2 and P holds 6)

15. Atoms in the same columns have the same number of valence electrons.
Helium only has 2 valence
electrons (not 8 like the rest
of the noble gases) 8 1 2 3 4 5 6 7

16. Electronegativity…
Is a measure of the ability of an atom in a chemical compound to attract electrons
Essentially to pull electrons away from the other atom(s)
Valence electrons hold compounds together
Uneven electrical charge is important in compound formation and other chemical properties

17. Electronegativity Across Periods… Down Groups/Families
Increases across periods
Fluorine is the most electronegative
Down Groups/Families
Decreases or stay same down a group
Noble gases do not form compounds so are not assigned electronegativity numbers

18. Electronegativity Trends