So, today we're going to look at the periodic table. That thing that you see behind ... For example, lithium (Li), sodium (Na) and potassium (K) all have the same kind of reaction with water.

So, today we're going to look at the periodic table. That thing that you see behind ... For example, lithium (Li), sodium (Na) and potassium (K) all have the same kind of reaction with water.

Since this atom has a total of eight electrons, it also has eight protons ... After the second level has 8 electrons, the next electron goes into the third level. 3rd Period: Sodium to argon—Electrons ...