Protons have a positive charge and determine atomic number, neutrons have no charge and equal mass to protons, electrons have a negative charge and equal number to protons in neutral atoms. Atomic symbols represent the atomic number Z of protons and mass number A of protons plus neutrons. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, giving them different mass numbers.

1. Protons Has a positive (+) charge Has a relative mass of 1 Determines the atomic number Found inside the nucleus

2. Neutrons Has a relative mass of 1 Found inside the nucleus Charge is = to zero Equal to the # of protons in a neutral atom

4. Has a relative mass of 0 (zero)

5. Found outside the nucleus

7. Isotopes Isotopes are two atoms of the same element Same atomic number Different mass numbers Number of neutrons is A-Z Number of neutrons differs between isotopes