1. Protons, neutrons and electrons How to find the number of each in any given atom.

2. Protons Periodic table. Periodic table. The atomic number on the periodic table tells you the number of protons. How many protons in C, Si and Ba?

3. Electrons Electrons are equal to protons in a neutral atom. Electrons are equal to protons in a neutral atom. Electrons are free to move, however, to make ions.

4. Ions Ions form from the loss or gain of electrons. Ions form from the loss or gain of electrons. The loss of an electron leaves a positive charge. So the gain of electrons leaves what charge?

5. Neutrons What is the function of neutrons? What is the function of neutrons? They are the “glue” that holds a nucleus together. How many neutrons are needed for each proton?

6. Neutrons Usually you need one neutron for every proton, but that is not always true. Usually you need one neutron for every proton, but that is not always true. Isotopes form when different numbers of neutrons are found in an atom.

7. Neutrons Mass number is the number of protons + neutrons in a given atom. Mass number is the number of protons + neutrons in a given atom. What are the mass numbers of each of these? Mass number and atomic mass are not the same!!!

8. Protons, neutrons and electrons Protons are equal to the atomic number. Protons are equal to the atomic number. Electrons are equal to the protons. Electrons are equal to the protons. Ions add or subtract electrons according to charge. Ions add or subtract electrons according to charge. Mass number – protons (atomic number) gives you the neutrons. Mass number – protons (atomic number) gives you the neutrons. Protons + neutrons gives the mass number. Protons + neutrons gives the mass number.