1. Periodic Trends

2. Atomic Radius Atomic Radius – the average size of the electron cloud

3. Finding atomic radius No definite boundary to electron cloud, so we measure distance from one nucleus to the neighbor nucleus and divide by 2.

4. Atomic Radius Trend Increases as you move down a group Decreases as you move from left to right across a period Where’s the biggest? Bottom left

5. Increases IncreasesIncreases Atomic Radius Trend

7. Ionization energy The energy required to remove an electron from an atom Pull off the farthest e- from the nucleus, less positive charge attracting the negative charge Energy needed to make an ion

8. Periodic Trend Decreases as you move down a group Increases as you move from left to right across a period Where’s biggest? Top right

9. Ionization Energy Trends

10. Trend Why opposite of atomic radius?? Radius is smaller so electrons are closer to nucleus, being held tighter by the positive charge in the nucleus Project: could represent by things getting bigger or by more of something (1 bean of energy vs. 5 beans of energy)

11. Electronegativity The tendency for the atoms of the element to attract electrons when they are chemically combined with atoms of another element How selfish is an atom in a bond? Hoarding all the electrons?

12. Electronegativity

13. Periodic Trend Decreases as you move down a group Generally increases as you move from left to right across a period (excluding the noble gases) Where’s the biggest?? Top right Project: show more of something, bigger, or two objects closer together (ex: a bead on a string, two of same pasta with 1 inch apart or 3 inches apart (sprinkles spaced on a cupcake)

14. Electronegativity Trends

15. Electron Affinity Atoms attracting for a single electron How bad does it want 1 more? Opposite of ionization energy (take away 1 electron)

16. Periodic Trend Decreases as you move down a group Generally increases as you move from left to right across a period (excluding the noble gases) Where’s the biggest?? Top right Project: Show more of something or getting bigger (bigger desire for 1 more electron!)

17. Periodic Trend

18. Ionic Size Positive ions are always smaller than the neutral atoms from which they form Taking away = smaller Negative ions are always larger than the neutral atoms from which they form Adding = bigger

19. Periodic Trend Increases as you move down a group Decreases as you move from left to right across a period Where’s the biggest? Bottom left

21. Compare trends Atomic radius – bottom left Ionic size - bottom left Ionization energy – top right Electronegativity – top right Electron affinity – top right

22. Practice: a.How does the radius of an anion compare to the radius of a neutral atom for that element? b.Which element in each pair has a larger ionization energy: Na or K; Mg or P? c.For which of these properties does lithium have a larger value than potassium? 1 st ionization energy, atomic radius, electronegativity, ionic radius?

23. Answers a.Anion is larger b.Na and P c.1 st ionization energy and electronegativity Check out this site: http://www.webteach.addr.com/CHSChemistry/perio dic_table.htm