Answer:
If the number of protons, neutrons, or electrons changes, it changes the properties of the atom in a major way.
#1 Changing the Proton Number
If you change the number of protons, you completely change the element.
Each element has a certain number of protons. If sodium gained a proton it would become magnesium.
Obviously, it’s a little more complicated than that, but you get the picture. Tell students to leave protons alone.
(By the way, if you are looking for a color coded way to teach finding protons from the atomic number, read this blog post.)
#2 Changing Neutron Number
If you change the number of neutrons, you create isotopes. Isotopes are basically just lighter or heavier versions of an average element.
In fact, the way we calculate the mass number of a given element on the periodic table is to average the light, medium, and heavy versions of that element.
#3 Changing Electron Number
If you change the number of electrons you create ions. A loss of electrons is going to lead to an anion. A gain of electrons is going to lead to a cation.
If you are teaching this principle to your students, make sure they know that most elements tend to form either a cation OR an anion. Not both.
Well, unless you are hydrogen, but he’s “special”.
Subatomic Particles Matter
After explaining all this to your students they will see that the smallest change, or mistake as it is likely to be, will change the whole atom.
It also really helps students to see these principles side by side because many times on tests we ask them what the loss of an electron will do to an atom of Na.
One of the options is usually “Create an isotope”, so this helps clarify the concept so that your students are better prepared for those concepts.
Hope, these help you give a clear and better understanding !