Question: how does the mass of an 16/8 o atoms compare with the mass of the original eight protons and eight neutrons that formed it?the mass of the 16/8 o atom is slightly less. *i need to know why this is correct*

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

gold is my favorite solid.