You taught them metals vs nonmetals. You taught them to name ionic compounds. You taught them to name covalent compounds. But, now when it comes to putting the big picture together everyone just got lost.

Why?

A lot of the time we teach all of these concepts separately. But, why not emphasize the differences to help students remember?

In fact, I have a doodle note set that explains this concept side by side.
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If the number of protons, neutrons, or electrons changes, it changes the properties of the atom in a major way.

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.
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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.)

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.

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.
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Well, unless you are hydrogen, but he’s “special”.

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 this principle side by side because many times on tests we ask them what the lost of an electron will do to an atom of Na.

One of the options is usually isotope, so this helps clarify the concept so that your students are better prepared for those concepts.

Here is a link for those subatomic particle doodle notes. 

Suggested Worksheets:

• Doodle Notes Packet
• Protons, Neutrons and Atomic Models (Best for classwork or homework)
• What Information is in a Mass Number? (A nice handout, or example that shows the difference in atomic vs mass number)