The atomic mass on the periodic table represents the sum of number of protons and number of neutrons.
Atomic mass = Number of protons + number of neutrons
Hope this helps!
Explanation:
The electrical force between two objects is given by the formula as follows :

k is electrostatic constant
q₁ and q₂ are electric charges
d is distance between charges
So, the two force between two charged objects depends on the product of charges and distance between charges.
a pure compound because an element is untouched and is just itself