1. Factors Affecting Periodicity Periodic Trends: Atomic Radius: the distance from the center of the nucleus to the outermost electron (how big an atom is) –Ionic Radius: the size of positive or negative ions Ionization energy: the amount of energy required to remove an electron from an atom or ion Electronegativity: the attraction an atom has for electrons

2. Factors Affecting Periodicity Factors Affecting Periodicity: Effective Nuclear Charge: the total positive force of the nucleus (the more protons, the higher the effective nuclear charge) Electron Repulsion: result of like- charged electrons electrostatic repulsion

3. Factors Affecting Periodicity Stable electron configuration: atoms strive to form s 2 p 6 configurations (full valence*, full octet*…*we’ll get to this) Number of Energy Levels Electron Shielding Effect: inner electrons temporarily “blocking” the nucleus’s electrostatic attraction for outer electrons Proton : electron ratio