MHS Chemistry
Atomic Theory Worksheet
  1. Complete the following table:
Element Symbol Atomic Number protons neutrons electrons charge mass number
Oxygen
         
0
16
 
Ru
   
58
 
2+
 
   
26
   
23
 
56
     
17
   
1-
35
         
18
2-
34
Nitrogen
     
8
10
   
  1. The masses of a proton, neutron, and electron are listed (in grams) on your Atomic Theory Summary handout.  Write them each out all the way in decimal notation.


  2. Define ion, and give two examples from the table above.


     
  3. Define isotope, and give two examples from the table above.


     
  4. How is it possible for the "average" family in America to have 2.3 children?


  5. An atom has 10 neutrons and a mass number of 19.  Which of the following is an isotope of this element?

    20    F       20Ne    19Ne      39K     65Cu
     
  6. Boron consists of two isotopes in nature.  81% of all boron atoms have a mass number of 11, and the rest of them have a mass number of 10.  Calculate the average atomic mass of boron.


     
  7. An imaginary element called Cafetorium (Ct)  is discovered to have three isotopes.  25% are Ct-288, 66% are Ct-290, and the rest are Ct-291.  What would be the atomic mass of Cafetorium?


     
  8. Why is the atomic weight on the periodic table usually written as a decimal number?


     
  9. Why is the atomic mass of nobelium (symbol No, atomic number 102) written as a whole number in parentheses, instead of as a decimal?
     

 


[Atomic Theory Summary][Chapter 3 Notes][MHS Chem page]