1. Periodic Table Trends

2. Electronegativity (electron affinity)
Periodic Table Trends
Atomic Size/Radius
Ionization Energy
Electronegativity (electron affinity)

3. Atomic Radius (size)
How large an atom is

4. Atomic Radius (notice any patterns?)

5. Atomic Size/ Atomic radius
down groups  Increases
Electrons in increased energy levels (shells)
across periods  Decreases.
There are more valence electrons in the same shell (energy level) so they pull towards the nucleus which has an increased number of protons.
More number of protons in the nucleus- more proton pulling power

6. Ionization Energy
Energy required to remove one electron from an atom in the gas phase.

7. Ions
When an element loses an electron it forms a positively charged ion called cation

8. Ions
When an element gains an electron it forms a negatively charged particle called anion.

9. Ionization Energies (notice any patterns?)

10. Ionization Energies (notice any patterns?)

11. Ionization Energy Down groups  Decreases Across periods  increases
as electrons are further from the nucleus there is lesser pull from protons
Across periods  increases
Electrons are added to the same energy level, so proton pulling power on electrons is higher.

12. Do Now
Which atom in each pair has the larger atomic radius and Ionization energy?
Li or K
Ca or Ni
Ga or B
O or C
Cl or Br
f) Be or Ba

13. Electronegativity-
Measure of how strongly an atom attracts a bonding pair of electrons to itself

14. Trend for electronegativity

15. Trends in Electronegativity:
down groups  decreases
The electrons are further from the nucleus, so less pulling from protons
across periods  increases
as atoms have more valence electrons in the same energy level and more protons in nucleus they have a higher pulling power.

17. Practice Problems
1. Which of the following elements has the smallest ionization energy;
Sodium, Calcium, Potassium, Magnesium
2. List the following elements in increasing ionization energy (smallest to largest)
Cesium, Bismuth, Oxygen, Beryllium
3. List the following elements in the increasing order of electro negativity
Chlorine, Flourine, Carbon, Magnesium