What does the bottom number within each box of the periodic table refer to? How can it be used to determine the number of neutrons inside an element?

The number above the symbol is the atomic mass (or atomic weight). This is the total number of protons and neutrons in an atom. The number below the symbol is the atomic number and this reflects the number of protons in the nucleus of each element's atom. Every element has a unique atomic number.

Because you ate playdough

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