After the third energy level has 8 electrons, the next electron goes into the fourth level. 4th Period: Potassium and Calcium—Electrons go into the fourth energy level. A small piece of sodium metal ...

Moist air reacts with potassium to form potassium oxide. This creates a layer over the surface of the metal. These observations show that the reactivity of these metals increases going down the group.

They include lithium, sodium and potassium, and are placed in the first vertical column on the left of the periodic table. All the Group 1 elements are very reactive, and all react with water to ...

These are almost one-quarter of the periodic table and are mainly found in the ... sulphur, chlorine, potassium, sodium, calcium and magnesium. How polio affects the body and what WHO is doing ...