1. Periodic Trends

2. ? Atomic Radius (Size) What’s the trend?
Decreases across a period due to increase in positive nuclear charge
Increases down a group due to increasing number of energy levels (shells)

3. Ionic Radius (size of ions)
Ion: an atom that has a positive charge (cation) or negative charge (anion)
Cations have a smaller ionic radius than corresponding atom
Protons outnumber electrons
Less shielding of electrons
Anions have a larger ionic radius than corresponding atom
Electrons outnumber protons
Greater electron-electron repulsion

4. Ionization Energy
The energy required to remove one electron from a neutral atom of an element (kj/mol) (form a cation)
Energy must be added to remove an electron to break the attractive forces between the electron and the protons in the nucleus
The easier it is to remove an electron, the smaller the ionization energy
Atoms with multiple electrons have multiple Ionization Energies
Ionization Energy increases for each successive electron
First Ionization Energy < Second Ionization Energy <Third…

6. Ionization Energy
Whats the trend?

7. Ionization Energy IE tends to increase across each period.
Atoms are getting smaller, electrons are closer to the nucleus
IE tends to decrease down a group
Atoms are getting larger, electrons are farther from the nucleus
Outer electrons becomes increasingly more shielded from the nucleus by inner electrons
Metals have characteristically low IE
Nonmentals have high IE
Noble gases have a very high IE

9. Electron Affinity
The change in energy that occurs when an electron is added to a gaseous atom (An Anion is formed)
The easier it is to add an electron, the higher the electron affinity
Electron Affinity decreases as you add more electrons
First EA > Second EA > Third EA…

10. Electron Affinity – What’s the trend
Electron Affinity – What’s the trend? Where on the periodic table is EA the least? Is it the most?
Halogens have the highest electron affinities
Metals have low electron affinities
Affinity tends to increase across a period and decrease down a group

11. Electronegativity
Electronegativity