1. Trends in the Periodic Table
Unit 10 Periodicity
Trends in the Periodic Table

2. Ionization Energy
The amount of energy required to remove the most loosely bound electron.
1st Ionization energy:
X + energy = X+ + e-
2nd Ionization energy:
X+ + energy = X2+ + e-

3. WS #1
Go to my website mtakano.weebly.com/chemistry and open the Excel file: “IE and radii-w graphs”
Graph Ionization Energy vs Electron Number
Boron
Silicon
Calcium

4. WS #1 cont. Let’s take a closer look…
Adjust the vertical axis to “zoom in.”
What patterns or trends do you see?
Adjust the scale to “logarithmic.”

5. Bohr Model Atoms contain a small, positively-charged nucleus.
Electrons “orbit” the nucleus (like planets orbiting the Sun) in discrete energy levels.

6. “Men in a Well”-Hydrogen
Removing an electron from an atom, like removing a man from a well, requires energy.
This is called ionization energy.
IE1 = 13.6 eV

7. “Men in a Well”-Helium
Which is easier to remove, the first man, or the second man?
IE1 = 24.6 eV
IE2 = 54.4 eV
Which is more important: attractions between protons and electrons or repulsions between electrons?

8. “Men in a Well”-Lithium
What should our diagram look like for lithium’s three electrons?
IE1 = 5.4 eV
IE2 = 75.6 eV
IE3 = 122 eV

9. Worksheet #3
An atom has a strong attraction if its first ionization energy is >10 eV.
An atom has a weak attraction if its first ionization energy is <7.8 eV.
Rules for completing Worksheet #2:
1) Elements with strong attractions generally form (-) ions, but not (+) ones.
2) Elements with weak attractions generally form (+) ions, but not (-) ones.
3) Elements with intermediate attractions generally do not form ions.
4) Elements that can lose valence electrons can generally lose all of them.
5) Elements that can gain valence electrons will generally gain enough to fill its valence level.