How can you find the number of neutrons in one atom of an element using only the periodic table?

Answer 1

Easy. Let us take for example Uranium and its two isotopes listed are U235 and U238. The atomic number of U is 92 indicates that it has 92 protons in the nucleus and the balance have to be neutrons and so we have 143 and 146 neutrons respectively. So, the mass number minus the atomic number gives you the number of neutrons in each isotope.

Answer 2

Hi Elizabeth,

To find the number of neutrons, you take the mass number and take away the proton number

Ex: Oxygen, Atomic Number 16 Atomic Weight 32

32-16 = 16 Neutrons.

More complex examples have isotopes, so make sure you have the right one!

Hope it helps!