1. Have your reference table out.
Assignment: read p
Do: Page 141 1, 3, 5, 9
Today’s Agenda
Homework review
Review of two periodic table trends in preparation for more on bonding.
You should be able to relate the two trends.
Have your reference table out.

2. The Trends Affecting Bonding: Ionization Energy and Electronegativity
Find out what these are and you will understand whole lot more about bonding and forces between molecules.
This effects chemistry concepts such as boiling point, melting point, vapor pressure, solubility, and gas laws so they are very important to understand!!

3. The higher the energy the harder it is to remove.
Ionization Energy
We know that ions form. For example, sodium “loses” an electron to become a positive ion.
Na(g) Na+ + e-
But, this takes energy, because the electron is attracted to the nucleus of the atom. The amount of energy it takes to overcome the force and remove the electron is called the Ionization Energy ***This occurs when the atom is not bonded
The higher the energy the harder it is to remove.

4. So, which elements would be the toughest ones to remove electrons from
So, which elements would be the toughest ones to remove electrons from? Easiest?
Let’s find the trends:
Look up first ionization energy:
neon
flourine
iron
sodium
francium
Answer the following questions:
Why would neon be so tough?
Why is sodium easy?
Who is the easiest?
What is the trend?

5. Did you notice that it says “first ionization energy”?
It is because more than one electron can come off.
But , in regents chemistry, you only have to worry about first ionization energy.

6. A Final Trend--Electronegativity
What is electronegativity??
Electronegativity is a concept that works when atoms are bonded to other atoms. It is the tendency of the atom to attract electrons. It tells you whether electrons transfer, are shared unequally or are shared equally. It is a scale based on 0-4, 4 being strongest.
Please look up:
Flourine Hydrogen Nitrogen
Cesium Sodium Carbon
What is the trend as you go down a column?
What is the trend as you go left to right?

7. A final summary of trends

8. Question: why would electron affinity and electronegativity trends be similar?

9. end