Compare an electrically neutral atom of oxygen and an isotope of oxygen. in own words
neutral implies that the amount of electrons = amount of protons
so for oxygen, protons = 8
isotopes have equal number of protons but differ in number of neutrons , so that affect the mass since :
protons + neutrons = atomic mass
Hope this helps
Explanation:
An isotope is defined as the specie which contains same number of protons but different number of neutrons.
For example, \(^{16}_{8}O\) and \(^{17}_{8}O\) are isotopes.
In a neutral oxygen atom, there are 8 protons and 8 neutrons.
As it is known that in a neutral atom the number of protons is equal to the number of electrons.
This means that in a neutral oxygen atom there are also 8 electrons.
Whereas in \(^{17}_{8}O\) is an isotope of oxygen atom whose atomic number is 8 and atomic mass is 17.
In \(^{17}_{8}O\), there are 8 protons and 9 neutrons.