1. The Bohr Model of the Atom  Niels Bohr, a young Danish physicist working in Rutherford’s laboratory in 1913, suggested that the single electron in a hydrogen atom moves around the nucleus in only certain allowed circular orbits.

2.  The atom looked like a miniature solar system.  The nucleus is represented by the sun, and the electrons act like the planets. The Bohr Model of the Atom

3. Nucleus Electron Orbit Energy Levels The Bohr Model of the Atom

4.  The orbits are circular and are at different levels.  Amounts of energy separate one level from another. The Bohr Model of the Atom

5. Bohr Diagrams 1) Find your element on the periodic table. 2) Determine the number of electrons 3) This is how many electrons you will draw.

6.  Find out which period (row) your element is in.  Elements in the 1 st period have one energy level.  Elements in the 2 nd period have two energy levels, and so on. Bohr Diagrams

7. 1) Draw a nucleus with the element symbol inside. 2) Carbon is in the 2 nd period, so it has two energy levels, or shells. 3) Draw the shells around the nucleus. Bohr Diagrams C C

8. 1) Add the electrons. 2) Carbon has 6 electrons. 3) The first shell can only hold 2 electrons. Bohr Diagrams C C

9. 1) The second shell can only hold 8 electrons. 2) The third shell can only hold 18 electrons. Bohr Diagrams C C

10. 1) Since you have 2 electrons already drawn, you need to add 4 more. 2) These go in the 2 nd shell. 3) Add one at a time - starting on the right side and going counter-clockwise. C C Bohr Diagrams

11. Try the following elements on your own: a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar Bohr Diagrams

12. Try the following elements on your own: a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar H H Bohr Diagrams 1 electron

13. Try the following elements on your own: a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar He Bohr Diagrams 2 electrons

14. Try the following elements on your own: a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar Bohr Diagrams O 2- 10 electrons

15. Try the following elements on your own: a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar Bohr Diagrams Mg 2+ 10 electrons

16. Try the following elements on your own: a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar Bohr Diagrams Ne 10 electrons

17. Try the following elements on your own : a)H b)He c)O 2- d)Mg 2+ e)Ne f)Ar Ar Bohr Diagrams 18 electrons

18. Electron Dot Diagrams ♦An electron dot diagram illustrates valence electrons as dots (or other small symbols) around the chemical symbol of an element.

19. ♦Each dot represents one valence electron. ♦In the dot diagram, the element’s symbol represents the core of the atom—the nucleus plus all the inner electrons. Electron Dot Diagrams

20.  Write the symbol. X ♦Put one dot for each valence electron. ♦Don’t pair electrons up until you have to. Electron Dot Diagrams

22. Write a Lewis dot diagram for chlorine. Electron Dot Diagrams

23. Write a Lewis dot diagram for calcium. Electron Dot Diagrams

24. Write a Lewis dot diagram for potassium. Electron Dot Diagrams