1. Periodic Trends

2. Review The elements of the P. T. are placed into:
rows by the number of energy levels they have.
groups by the number of valence electrons they have.
blocks by what kind of sublevel they are filling.
Atoms can gain or lose electrons.
Metallic atoms lose e- and form cations.
Nonmetallic atoms gain e- and form anions.

3. Metallicity
More Metallic
Less Metallic
Less Metallic
More Metallic

4. The Big Questions What is atomic radius?
How is ionic radius related to atomic radius?
What is the trend concerning atomic radius?
What is ionization energy, and what trend is associated with it?
What is electronegativity, and what trend is associated with it?

5. Atomic Radius
Atomic radius – distance from center of atom to outer electrons.
Decreases across a period.
Increases down a group.

6. Atomic Radii in Period 2 Li Be B C F N O Increasing atomic numberNe
Increasing atomic number
means greater attraction
for electrons!

7. Atomic Radii of the HalogensCl Br I At
Increasing number of energy
levels means a larger atom.

8. Atomic Radii General Trend
Radius Increases
Radius Decreases
Radius Decreases
Radius Increases

9. Ionic Radius Cations are smaller than their atoms.
Anions are larger than their atoms.

10. Ionic Radius

11. Ionization Energy
Ionization Energy – energy required to remove 1 electron from an atom.

12. Ionization Energy +

13. Ionization Energy
Increases across a period.
Decreases down a group.

14. Electronegativity
Electronegativity (EN) - Tendency of an atom to attract electrons in a chemical bond.
Increases across a period.
Decreases down a group.
Excludes noble gases.

15. Electronegativity