1. Masses of Atoms

2. The mass of the protons and neutrons (electrons have almost NO mass)
Atomic Mass
The mass of the protons and neutrons (electrons have almost NO mass)
Atomic mass = mass #

3. # of protons in an atom Atomic Number
The atomic # is the identity of an element
Like a fingerprint for a human being

4. *If you need to find the number of neutrons in an atom:
# neutrons= mass # - atomic #

5. Isotopes
Atoms of the same element that have different numbers of neutrons
Boron-10 ; Boron-11
Different isotopes have different properties

6. Average Atomic Mass
Weighted average of an element’s isotopes

7. Practice Isotope name atomic # mass # # of protons # of neutrons
# of electrons
Potassium-37
Oxygen-17
uranium-235
uranium-238
boron-10
boron-11