1. Determining the Subatomic Particles of an Atom

2. To find the number of protons, electrons, and neutrons in a specific atom follow the following four steps.

3. Step 1 Gather data – Find the atomic number and the atomic mass of the element. Atomic Number Atomic Mass

4. Step 2 Identify the number of protons The atomic number represents the number of protons in an atom. If you add or subtract protons you end up with an entirely different element.

5. Step 3 Identify the number of electrons Atoms are neutral, so to balance the number of positive charges you must have an equal number of negative charges. So the number of electrons is the same as the number of protons to keep the atom neutral.

6. Step 4 Identify the number of neutrons Round the atomic mass to the nearest whole number. Example 14.65 = 15 The atomic mass represents the number of protons and the number of neutrons in the nucleus. So subtract the atomic number from the atomic mass to find the number of neutrons in the atom.

7. APE MAN A = Atomic number P = Protons E = Electrons M = (Atomic) Mass A = Atomic (Number) N = Neutron

8. MAN Atomic Mass - Atomic Number = Neutron

9. Now you try it! Oxygen Atomic number = 8 Atomic mass = 15.999 How many neutrons does this atom have?