1. Periodic Table Trends

2. Atomic Radius  Measured in Pico meters- 1 x 10 -12 m  Estimated as one-half the distance between adjacent nuclei  Periodic Trend Radius generally decreases with increasing atomic number (left to right) - Due to increasing nuclear charge (increasing attraction)  Group Trend Radius increases with increasing atomic number (top to bottom) - Due to increasing number of energy levels

3. Atomic Radius

4. Ionization Energy  Energy it takes to remove the first outermost valence electron from an atom.  Each additional electron requires more energy than the previous.  The required energy increases dramatically when the electron is removed from a full valence.  Group Trend- with increasing atomic no., the ionization energy decreases (top to bottom)  Periodic Trend- with increasing atomic no., the ionization energy generally increases (left to right)

5. First Ionization Energy

6. Electron Affinity  Definition – the energy change that accompanies the addition of an electron to a gaseous atom.  Nonmetals readily gain electrons, therefore they have the highest negative electron affinities (energy loss - exothermic).  Metals normally lose electrons, therefore they most likely have positive electron affinities (endothermic).

7. Electron Affinity

8. Ionic Radius Ionic radii are different from atomic radii because electrons have been lost or gained. Metals – oxidize (lose electrons) ionic radius is smaller than atomic radius Nonmetals – reduce (gain electrons) ionic radius is larger than atomic radius

9. Some Atoms and Their Ionic Radii

10. Metallic Character  Ability of an atom to act like a metal or to lose an electron.  No numerical value – relative  Periodic Trend: with increasing atomic number, metallic character decreases  Group Trend: with increasing atomic number, metallic character increases

11. Electronegativity  Definition – the tendency for an atom to attract electrons to itself when it is chemically combined with another element.  Relative scale – no units  Highest measurement : Fluorine 4.0 (most active nonmetal);  Lowest measurement Cs or Fr, 0.7 (most active metals)  Periodic Trend – with increasing atomic number, electronegativity increases (left to right)  Group Trend – with increasing atomic number, electronegativity decreases (top to bottom)

12. Electronegativity