1. Topic: The Periodic Table Aim: What trends exist on the Periodic Table?
Do Now:
An unknown element is tested and is found to be ductile, malleable, and a good conductor. How would you classify this element? (metal, nonmetal, or metalloid)?
HW:

2. Period Horizontal row – there are 7
Each period corresponds to adding another PEL!
Period

3. Trends in a Period (as you go across )
Atomic # increases
See Periodic Table
# of valence e- increases as # of p+ (atomic #) increases. Therefore, the valence shell is filling up! THE ELEMENT IS BECOMING CLOSER TO ACHIEVING STABILITY

4. Periodic Trends, cont.
Atomic radius decreases b/c there are more p+ in the nucleus (more + charges) which pull in the e- more
Greater coulombic forces
See Table S
Elements across a period have the same # of PELs
Ex. Period 4, 4 PELS, Period 2, 2 PELs
How do you know? CHECK THE e- CONFIG

5. Periodic Trends, cont. Ionization energy generally increases
See Table S
Ionization energy – amount of energy needed to remove an electron.
This means that the atom is holding onto its e- more & more  why?
B/c the valence PEL is getting closer to CAPACITY (8)  STRONGER COULOMBIC FORCES
Think – if you’re collecting something and your set is almost complete, you don’t want to let the pieces go! Conversely, if you’re just starting your collection, you might not be as sad to see them go.

6. Periodic Trends, cont. Electronegativity generally increases
Electronegativity – attraction of an atom for electrons
↑ eneg, >♥ for e-
Want to hold on to e- more & more as you move across the period
↓ eneg, < ♥ for e-

7. Periodic Trends, cont. Change from + to – oxidation states
+ oxidation state = easier to LOSE an e- to form a + ion
- oxidation state = easier to GAIN an e- to form a - ion

8. Group Vertical column – there are 18
Each group corresponds to adding another valence electron
Group

9. Trends in a Group (as you go down ↓)
Atomic # increases
See Periodic Table
# of valence e- is the same – so ELEMENTS IN THE SAME GROUP HAVE SIMILAR CHEMICAL PROPERTIES

10. Group Trends, cont.
Atomic radius increases b/c a PEL is added each time you move downward
See Table S
Metallic character increases

11. Group Trends, cont. Ionization energy generally decreases
See Table S
b/c the valence e- are farther away  adding a PEL
They are easier to lose
Weaker Coulombic forces
Electronegativity generally decreases
Again, b/c the e- are farther away

12. Group Trends, cont. Same oxidation states
Members of the same group have similar chemical & physical properties
They do chemistry similarly b/c they have the same # of valence e-

13. Sample Questions