Transcript Periodic Trends 2

Ionization Energy
• Def: the energy required to remove an efrom 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.
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
Octet Rule
• If Na loses an electron:
1. What is its charge?
2. What is its new electron configuration?
3. 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.
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?