Explain how you can determine the number of neutrons an atom has from an atom's mass number and its atomic num

Answer 1

Atomic mass minus atomic number equals neutrons.

Answer 2

The atomic number is fuond by determining the number of protons within an atom. The atomic mass is the mass of the entire atom. Since electrons have relatively no mass, the number of neutrons would be found by subtracting the atomic number from the atomic mass. The remaining number will usually be a whole number and that is your number of neutrons. Neutrons have the same weight as protons. If there are a few numbers behind the decimal, toss them aside; this is the weight of the electrons.

Answer 3

num of neutrons=atomic mass-atomic num
That works because the atomic num is the number of protons and the atomic mass is the total mass of the element. Since electron mass is really really really small you can consider it to be 0. so the rest of the weight is only protons and neutrons. Since 1 proton weighs 1 atomic mass unit and so does one neutron, the atomic mass would be the total number of protons +neutrons. the atomic number gives you the number of protons so if you subtract it from the atomic mass you would get the number of neutrons.

Hope that helps!

Answer 4

Almost wat other ppl said. Only thing is that they are only approximately right. Amu (atomic mass unit) is equal to 1gram devided by avagadro number (app. 6.022*10 to the power of 23.)
the mass of a proton is a bit different than amu and so is neutron, but the fact of the matter is that if u substract atomic number (number of protons available in an atom) from atomic mass and round it to closest whole number, Ull get the number of protons.

Answer 5

atomic mass number = protones + nutrons
atomic number = protones

therefore nutrons = atomic mass number - atomic number