Download Isotopes and Atomic Mass Notes

Chemistry I: Notes: Basic Atomic Structure, Isotopes, and Atomic Mass
Atomic Structure
Let us review the basic structure of the atom. Below, draw a carbon atom. Next to it, draw a phosphorous
atom. (Prediction: Your chemistry teacher will explain the word "isotope" very soon.)
How would you represent each of the above atoms symbolically?
Write the complete symbol for an atom that has 92 protons 146 neutrons:
Write the complete symbol for an atom whose mass number is 21 and which has 11 neutrons:
Isotopes & Atomic Mass
What's the atomic mass of the 12C isotope?
If the 13C isotope is 1.0836129 times the mass of the 12C isotope, what is the atomic mass of the 13C
isotope?
If in every living thing on earth, 98.89% of the carbon is 12C and 1.11% of the carbon is 13C, what is the
average atomic mass of carbon?
What is the significance of average atomic mass?
Example:
Fill in the remaining cells in the following table, and perform calculations after the table:
Isotope
20
Ne
21
Ne
22
Ne
% Abundance
90.00
0.27
9.73
Calculate the atomic mass of neon.
Atomic mass (amu)
19.99212
20.99316
21.99132
# of protons
# of electrons
# of neutrons