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

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

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

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

Review of Trends Episode 403

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

You can label your periodic table Episode 403