Exercises: 1. Draw an atom for each of the following elements according to the Bohr-Rutherford Model.
a)H (1p) 1e
b) N (7p)2e)5e
c) Na (11p)2e)8e)1e)
d) Ca (20p)2e)8e)8e)2e
e) O (8p)2e)6e
2. Draw a Lewis structure for each of the following.
a) H 
b) N 
c) Na 
d) Ca 
e) O 
- How did Bohr realize that electrons belonged to different energy levels?
The emission spectrum of hydrogen consists of discrete lines. He figured that each narrow line of colour corresponded to the fall of an electron from an excited energy level to a lower level that was closer to the nucleus. If the electron could fall anywhere then there would not be distinct lines. There would be bands of colour like in a rainbow.