Yes, the number of neutrons in an atom can be determined using the periodic table by subtracting the atomic number from the mass number. The atomic number (Z) tells how many protons are in the nucleus and is found on the periodic table for each element. The mass number (A) is the total number of protons and neutrons combined, and for elements on the periodic table, this is often the rounded atomic mass. The formula is:
Number of neutrons=Mass number−Atomic number\text{Number of neutrons}=\text{Mass number}-\text{Atomic number}Number of neutrons=Mass number−Atomic number
Since the atomic number is always an integer and represents the number of protons, you round the atomic mass from the periodic table to the nearest whole number to get the mass number and then subtract the atomic number from it. For example, for an element with atomic number 29 and mass number 63, the neutrons would be 63−29=3463-29=3463−29=34. Note that the atomic mass on the periodic table is usually an average of isotopes, so the exact neutron number varies slightly for isotopes, but this method gives the neutron count for the most common isotope of the element.
