1. Periodic Trends Atomic Number Atomic Mass Increases across a period
Increases down a family or group
Atomic Mass
Increases
Increases
Episode 403

2. Atomic Radius ½ the distance between nuclei of two like atoms
Decreases across a period
Due to the increased attraction of more positive nuclei to electron clouds
Increases down a family or group
Due to the addition of energy levels
Episode 403

3. Electron Affinity
Amount of energy released when an atom gains an electron
Electronegativity
Ability to attract or gain electrons
Increases across a period
Decreases down a family or group
Episode 403

4. Ionization Energy
Amount of energy required to remove an electron from a neutral atom
Increases across a period
Decreases down a family or group
Episode 403

5. Review of Trends
Episode 403

6. Electron Distribution – Forming Ions
Atoms become ions by losing or gaining electrons to become charged
An atom is stable when it has a full outer energy level
(8 valence electrons)
Atoms that lose (give away) electrons become + charged
Cation
Atoms that gain (steal) electrons become – charged
Anions
Episode 403

7. You can label your periodic table
Episode 403