Your supposed to find an element and other info from the periodic table and fit in in each row. For example the first row is B and the Atomic number would be 5 and protons would be 5 because the atomic number is the same as the atomic mass. Also, you would need to look up a periodic table for this. and google. Boron's neutrons would be 6 and electrons would be 5. The mass number would be 10.811.
