Isotopes and Atoms!

Today we learned about atoms and isotopes. No atom is perfectly the same; some atoms have variations of mass (due to the difference in neutron number) and these are called isotopes. We also learned how a spectrometer works and how it gets the average of the different isotopes.

Important Definitions
Atomic Number - Number of protons in an atom
Isotopes - Same atomic number but different mass
Spectrometer - are used to determine the abundance and mass of the isotopes of elements

Isotopes of Hydrogen


Spectrometer: Calculating averages


We have in the image shown above the relative abundances of europium. To find the average mass we need to do a series of calculations...

Step 1: Multiply the percentage (convert to decimals) with the mass number
151(0.478) + 153(0.522) = Average Mass
Step 2: Add the results
72.178 + 79.866 = Average Mass
Step 3: You get your average
152.0 = Average Mass of Europium

*Check the periodic table! Europium has an atomic mass of 152.0!