Course Summary
Below is a summary of the three lessons from this mini-course. You may wish to print this page to keep as a study aid.
Counting Particles
- Find the number of protons from the Atomic Number
- Find the number of neutrons by subtracting the number of protons from the Isotopic Mass. This is the number associated with the isotope, not the Atomic Mass from the periodic table. For example, for 14C, you would use the "14", not the 12.01 found on the table.
- Set the number of electrons equal to the number of protons. This can change for ions, but that is for another lesson.
Average Atomic Mass
- If you are given the number of atoms, convert these to percentages.
- Convert the percentages to decimals (move the decimal point two places to the left)
- Multiply these decimals by the masses of the individual isotopes.
- Add the products together, and make the unit "g/mol".
- Double check your answer with the atomic mass found on the periodic table. It should be close.
Applications
- The isotope 14C can be used to date objects that were once alive. We measure the amount of 14C that has not changed into other things to determine about when something died.
- The isotope 60Co can be used to treat cancer, and various other isotopes are used for medical tracing.
- The isotope 235U is used as the fuel source in nuclear reactors. The clouds that come from nuclear reactors are steam, not nuclear pollution.
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