We learned that there are many kinds of matter and an element is the type of matter made of just one kind of atom. Then we learned that all known elements are organized by their properties in the Periodic Table of Elements. Next we learned that different atoms of the same element can contain different numbers of neutrons and electrons can be gained or lost but the number of protons in an element always stays the same. This is why elements in the Periodic Table of Elements are given an atomic number equal to the number of protons.
Assignment: We completed a diagram of a chlorine atom.