1. WHAT ARE THE PERIODIC TRENDS?

3. Periodic Trends All information in contained in table S Predictable properties/changes that occur as we move down groups and across periods Based on the properties of elements Repeated from group to group and period to period

4. Atomic Radius Size of an atom Based on the number of protons an atom has and the number of energy shells Period Trend: As we move left to right atomic radius decreases As we increase the number of protons the EFFECTIVE NUCLEAR CHARGE increases (more protons makes an atom stronger) This is why the smallest elements in a period are always in Group 17 Fluorine is the smallest and strongest element on the table (Greatest effective charge)

5. Atomic Radius Cont: Group Trend: As we move down a group atomic radius INCREASES This is because the number of energy levels increases Each level adds a shell and so the atom occupies more volume

7. Ionization Energy Measurement of how much energy it takes to remove the outermost electron from an atom Period Trend: Increases moving left to right as the EFFECTIVE NUCLEAR CHARGE increases More protons = more nuclear strength This is why metals lose electrons and non-metals never lose electrons Strongest elements are always the non-metals in group 17

8. Group Trend in Ionization Energy Group Trend: Down a group IE decreases Each additional energy level makes it more difficult for the nucleus to hold onto electrons Francium would be the weakest element

10. Electronegativity Trends Measurement of how strongly you attract other elements electrons to you Non-metals are good at this, metals are not Period Trend: Same as IE, so across a period electronegativity increases because of increases in EFFECTIVE NUCLEAR CHARGE Fluorine is the best (4.0) This is why non-metals gain electrons and metals lose, greater attractive forces

11. Group Trends in Electronegativity Group Trend: Down a group it decreases just like IE This is because of the effects of adding an energy level (more volume) Weakest elements are always at the bottom of a group (most metallic) This is again why metals lose electrons and non-metals gain

13. Trends in Ionic Size Positive ions are smaller than the atom they came from due to the loss of an energy level They always move back to the closest noble gas Negative ions are always larger than the atom they came from due to the increase in volume They always move forward to the closest noble gas For positive ions, the greater the magnitude of charge, the smaller the ion (+2 is smaller than +1) For negative ions, the greater the magnitude of charge, the larger the ion (-3 is larger than -2)