1. Topic: Trends in the Periodic Table: Ionization Energy and Electronegativity Do Now: p.13 #1-5

2. Trends more than 20 properties change in predictable way based location of elements on PTmore than 20 properties change in predictable way based location of elements on PT some properties: - anyone know where we can find these numbers?!some properties: - anyone know where we can find these numbers?! –Density –melting point/boiling point –atomic radius –ionization energy –electronegativity

3. REVIEW: How do you know if an atom gains or loses electrons? Think back to the Lewis structures of ionsThink back to the Lewis structures of ions Atoms form ions to get a valence of 8Atoms form ions to get a valence of 8 (or 2 for H) (or 2 for H) Metals tend to have 1, 2, or 3 valence electronsMetals tend to have 1, 2, or 3 valence electrons –It’s easier to lose them Nonmetals tend to have 5, 6, or 7 valence electronsNonmetals tend to have 5, 6, or 7 valence electrons –It’s easier to add some

4. OR

5. Ionization Energy the amount energy required to remove a valence electron from an atom in gas phasethe amount energy required to remove a valence electron from an atom in gas phase 1st ionization energy = energy required to remove the most loosely held valence electron (e - farthest from nucleus) = found on table S1st ionization energy = energy required to remove the most loosely held valence electron (e - farthest from nucleus) = found on table S

6. Cs valence electron lot farther away from nucleus than LiCs valence electron lot farther away from nucleus than Li electrostatic attraction much weaker so easier to steal electron away from Cselectrostatic attraction much weaker so easier to steal electron away from Cs THEREFORE, Li has a higher Ionization energy then CsTHEREFORE, Li has a higher Ionization energy then Cs previousprevious | index | nextindexnext

7. Decreased Ionization Energy (easier to remove an electron) Increased Ionization Energy (harder to remove an electron)

8. Electronegativity ability of atom to attract electrons in bondability of atom to attract electrons in bond noble gases tend not to form bonds, so don’t have electronegativity valuesnoble gases tend not to form bonds, so don’t have electronegativity values Unit = PaulingUnit = Pauling Fluorine: most electronegative elementFluorine: most electronegative element = 4.0 Paulings = 4.0 Paulings

9. Decreased Ionization Energy (easier to remove an electron) Increased Ionization Energy (harder to remove an electron) Decreased Electronegativity Increased Electronegativity

11. Reactivity of Metals judge reactivity of metals by how easily electronsjudge reactivity of metals by how easily give up electrons (they’re losers) So the easier it is to remove an electron the more reactive –Lower ionization energy = more reactive = more metallic

12. Decreased Ionization Energy (easier to remove an electron) Increased Ionization Energy (harder to remove an electron) Decreased Electronegativity Increased Electronegativity Most reactive metal = Fr (the most metallic) More metallic

13. Reactivity of Non-metals judge reactivity of non-metals by how easily electrons (they are winners)judge reactivity of non-metals by how easily gain electrons (they are winners) So the greater the affinity for electrons, the more reactive –Higher electronegativity= more reactive

14. Decreased Ionization Energy (easier to remove an electron) Increased Ionization Energy (harder to remove an electron) Decreased Electronegativity Increased Electronegativity Most reactive metal = Fr (the most metallic) More metallic Most Reactive Nonmetal = F Nonreactive BACK NonreactiveNonreactive

15. Allotropes Different forms of element in same phaseDifferent forms of element in same phase –different structures and properties O 2 and O 3 - both gas phaseO 2 and O 3 - both gas phase –O 2 (oxygen) - necessary for life –O 3 (ozone) - toxic to life Graphite, diamond:Graphite, diamond: –both carbon in solid form