What Do the Numbers Represent in the Block for the Element Potassium on the Periodic Table?

Atomic Number and Mass Number are the two numbers in the block for the element Potassium on the periodic table. The atomic number, represented as 19, indicates the number of protons or electrons in a non-ionized state. On the other hand, the mass number, represented as 39.098, is the sum of the atomic number and the number of neutrons.