1. Ionization Energy
Def: the energy required to remove an e- from a gaseous atom.
1st ionization energy is the energy required to remove the 1st e- .
More energy is required to remove e-’s held more tightly by the nucleus.

2. Ionization Energy (continued)
So, how do you think ionization energy would change across periods?
Answer: Increases, due to increasing charge in the nucleus while adding electrons to the same principal energy level (same reasoning as atomic radius)
Down groups?
Answer: Decreases, due to same reasoning as atomic radius

3. Octet Rule If Na loses an electron:
What is its charge?
What is its new electron configuration?
How many electrons are present in its highest principal energy level (valence electrons)?
Octet Rule: atoms gain, lose, or share electrons in order to acquire a full set of 8 valence electrons.

4. Electronegativity
Def: the relative ability of an element’s atoms to attract electrons in a chemical bond
Most electronegative element is fluorine.
Least electronegative is francium.
What do you think the trend is within periods?
Within groups?