1. After today, you will be able to… Explain the periodic trend for ionic size and electronegativity Compare the size of cations to the size of anions

2. Unit 4: The Periodic Table Trends with Ionic Size and Electronegativity (E.N.)

3. Ionic Size: Cations Cations: (+) are always smaller than the neutral atom from which they are made. Sometimes there is a loss of energy levels There will be more protons than electrons, therefore electrons are pulled in closer

4. Ionic Size: Cations The more electrons lost, the smaller the ion becomes Example: Mg > Mg +1 > Mg +2 (largest in size) (smallest in size)

5. Ionic Size: Anions Anions: (-) are always larger than the neutral atom from which they are made. More electrons than protons results in less attractive force.

6. Ionic Size: Anions The more electrons gained, the bigger the ion becomes (less attractive force between electrons and nucleus). Example: O < O -1 < O -2 (smallest in size) (largest in size)

7. Trends with Electronegativity (E.N.) Tendency for an element to attract electrons when chemically combined with another element. Fluorine has the highest E.N. = 4.0

8. Group trend: E.N. decreases as you go down a group –Electrons are less attracted to the nucleus (more energy levels) Period trend: E.N. increases as you go across a period –Electrons are more attracted to the nucleus due to increased nuclear charge

9. Electronegativity Values

10. Summary: Electronegativity Easy way to remember: THE UPSIDE-DOWN SNOWMAN Decreases Increases

11. Do now: Complete and Turn in “Exit Ticket” Then: Begin WS 4 (Homework)