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 ...

Potassium tarnishes so quickly that it is difficult to see that potassium is actually a shiny metal. This is further evidence that potassium is a more reactive metal than both lithium and sodium.

A major jump in modern medicine for Ohio State’s Wexner Medical Center has arrived. The hospital is among the first in the country to utilize brand-new ...