1. Atomic Structure and Periodicity Periodic Trends

2. Ionization Energy  An electron can be removed from an atom if enough energy is absorbed (+)  Ionization energy – the energy required to remove one electron from a gaseous neutral atom A (g) + energy  A + (g) + e -  measurements of this are made on individual atoms in gas phase to avoid interactions with nearby atoms

3. Ionization Energy

5.  if one electron is removed, the positive charge binds the electrons more tightly so 2 nd ionization energy must be higher  the largest jump in energy is when you remove a core electron instead of valence

6. Ionization Energy

7.  Across Period: requires more energy to remove an electron so increases requires more energy to remove an electron so increases because electrons added in the same energy level do not shield electrons from nuclear charge because electrons added in the same energy level do not shield electrons from nuclear charge  Down Group: requires less energy to remove electron so decreases because the valence electrons are farther away from protons attracting them

8. Ionization Energy

10. Electron Affinity Electron Affinity – the energy change when an electron is added to a gaseous neutral atom exothermic (-) exothermic (-) A + e -  A - + energy

11. Electron Affinity  Across Period: releases more energy so number increases (gets more negative) releases more energy so number increases (gets more negative) because electrons added in the same energy level do not shield electrons from nuclear charge because electrons added in the same energy level do not shield electrons from nuclear charge  Down Group: releases less energy so number decreases (gets less negative) because the electrons being added are farther away from the attracting protons

13. Electron Affinity

14. Atomic Radii  Defined by the edge of its orbital but since the edges are fuzzy, difficult to determine  Atomic Radii – half the distance between the nuclei of identical atoms that are bonded together

15. Atomic Radii  Across Period: atoms get smaller atoms get smaller because of the increased number of protons attracting the electrons because of the increased number of protons attracting the electrons the electrons added in the same energy level do not shield electrons from nuclear charge the electrons added in the same energy level do not shield electrons from nuclear charge  Down Group: atoms get larger increases because the energy levels being added to the atom

18. Atomic/Ionic Radii