2. A typical problem – you are given a pair of elements, and asked to predict which would be more reactive. You can do this using periodic trends.

3. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity Rb Sr 1 2 3 4 5 6 Write the element in each pair that has a higher value for each trend.

4. QUESTION #1 – Is this a group trend or a period trend?

6. Trends for EFFECTIVE NUCLEAR CHARGE: PERIOD TREND left to right ___________ GROUP TREND top to bottom _________ 2. As EFFECTIVE NUCLEAR CHARGE increases, the valence electrons are held LESS MORE tightly by the nucleus.

7. 3. ATOMIC RADIUS is defined as: So the BIGGER the atomic radius, the BIGGER SMALLER the atom

8. 3. As effective nuclear charge increases, ATOMIC RADIUS INCREASES DECREASES Trends for ATOMIC RADIUS: PERIOD TREND left to right ___________ GROUP TREND top to bottom _________

9. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity Rb Sr 1 2 3 4 5 6

10. 4. IONIZATION ENERGY is defined as the energy required to

11. 4. As effective nuclear charge increases, IONIZATION ENERGY INCREASES DECREASES Trends for IONIZATION ENERGY: PERIOD TREND left to right ___________ GROUP TREND top to bottom _________

12. 5. What is electronegativity?

13. 5. As effective nuclear charge increases, ELECTRONEGATIVITY INCREASES DECREASES Trends for ELECTRONEGATIVITY PERIOD TREND left to right ___________ GROUP TREND top to bottom _________

14. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity Rb Sr 1 2 3 4 5 6

15. 6. REACTIVITY: These elements are: METALS NONMETALS

16. METALS react by LOSING GAINING so the metal with the LOWEST HIGHEST effective nuclear charge, and the LOWEST HIGHEST ionization energy is the more reactive.

17. NONMETALS react by LOSING GAINING electrons, so the metal with the LOWEST HIGHEST effective nuclear charge, and the LOWEST HIGHEST electronegativity is (usually) the more reactive.

18. Effective nuclear charge and electronegativity are not always directly related. EXPLAIN

19. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity S Se

20. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity FOFO

22. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity Kr Br

23. elementEffective nuclear charge atomic radius ionization energy electro- negativity reactivity Ba Ra