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 ...

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 ...

The periodic table captures a subtle pattern that runs ... is a reactive metal — just like sodium (element number 11) and potassium (number 19). A good way to think about it is to imagine ...

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 ...