Question

To find the number of neutrons in an atom, you would subtract

A. Mass number from Atomic number
B. Atomic number from Mass number
C.Atomic number from Electron number
B. Isotope number from Atomic number

Answer 1

B. Atomic number from mass number

Step-by-step explanation:

The general form for an atomic symbol of an element X is

`_(Z)^(A)\text{X}`

where

Z = the atomic number = the number of protons = p

A = the mass number =the number of protons plus neutrons =p + n

So, to get the number of neutrons, you take

A – Z = (p + n) – p = n

In words,

Mass number – atomic number = number of protons