Symbolic Representation of Atoms

1. Atomic Symbols
   1. The subscript number is called the atomic number = number of protons.
   2. The superscript number is called the mass number = protons+neutrons

      	Protons	Neutrons
      	6	8

2. The number of protons defines the element. All carbon atoms have 6 protons. All nitrogen atoms have 7 protons.
3. Atoms of the same element can, however, have different masses. Each unique form of an element has a specific number of protons and neutrons.

   	Protons	Neutrons
   	6	8

4. Each form of carbon above would be called an isotope of carbon. Sometimes they are referred to as Carbon-14 or Carbon-12. All isotopes of carbon have the same number of protons, but their number of neutrons can differ.
5. Atomic mass is the weighted average of the isotopes of a particular element. For example ~99% of carbon is Carbon-12 and ~1% is Carbon-14. In any sample of carbon on earth you will generally find this ratio. When you use a sample of carbon it contains both isotopes, so you need a way of determining the average atomic mass. Calculate the average atomic mass based on the abundances of the isotopes listed above. It should match the atomic mass listed on the periodic table - 12.01.
6. Atoms of course are made of one other elementary particle - the electron. Neutral atoms would exactly balance positive and negative charge. Each proton carries a charge of +1 and each electron carries a charge of -1. Any atom that is not neutral is called an ion.

   	Protons	Neutrons	Electrons
   	6	8