1. CO 2 NH 3 H2OH2O CH 4 Lewis structures Please draw the outer (valence) shell picture for CO 2 and NH 3

2. NH 3 N needs three covalent bonds to fill its valence (outer) shell. NH H H

3. CO 2 C needs four covalent bonds to fill its outer (valence) shell. O requires two covalent bonds to fill its outer shell C O O maximum number of pairs of electrons two main group atoms can share is 3 pairs.

4. electron step (energy) diagrams

5. What are the names of these neutral atoms?

6. He CMg What are the names of these neutral atoms?

7. in electron shell model, lower steps have lower energies. steps  shells

8. low energy high energy converting shell to step diagram Mg 1 st step (bottom) 2 nd step 3 rd step Mg

9. low energy high energy converting shell to step diagram Mg 1 st shell 2 nd shell 3 rd shell please draw carbon as a step diagram Mg

10. completely filled step (shell) empty step (shell) C partially filled step (shell) converting shell to step diagram C

11. traditio Energy Standard to draw the steps directly on top of one another Spatial representation of electrons in atom Energy representation of electrons in atom neutral carbon atom C C in this course you will be required to know further information to draw arrows and to divide step diagrams. almost standard step diagram

12. high energy unstable low energy stable Li electron is high in energy. F electrons are low in energy. How do these facts change radius of the Li and F shells?

13. high energy unstable low energy stable Li electron is high in energy. Its outer shell is large. F electrons are low in energy. The outer shell is small. How does different shell size affect atom size?

14. high energy unstable low energy stable 0.7 A o o 1.5 A Li electron is high in energy. e - are far away from nucleus. F electrons are low in energy. They are close to nucleus.

15. high energy unstable low energy stable Which atom is smaller: H or He? Be or N? Cl or F? Li or P? Caveat: When comparing elements in different rows, energies given above underestimate the size of the higher row element. (quantum shell effect)

16. high energy unstable low energy stable Which atom is smaller: H or He? Be or N? Cl or F? Li or P? Caveat: When comparing elements in different rows, energies given above underestimate the size of the higher row element. (quantum shell effect).53 Å vs..31 Å 1.05 Å vs..65 Å

18. Please draw the step diagrams for Li vs. F

19. Step diagram for Li vs. F Energy What sort of differences do we expect in almost standard step drawing?

20. standard step (energy) drawing Energy in this course you will be required to know further information to draw arrows and to divide step diagrams.