# "In each atom of a substance,the no. of electron and protons are same but the no. of neutrons may vary."  Justify this statement giving some appropriate examples.

bandmanjoe | Certified Educator

This is the definition of an isotope.  In basic atomic structure, each atom has a specified number of protons, neutrons, and electrons.  The proton and electron numbers are equal, as the protons have positive charges, while the electrons have negative charges.  Neutrons have no charge whatsoever, so their number can vary, producing different variations of the same element.  We call these different variations isotopes.  When you look at the periodic chart, look at the bottom number, which is called the atomic mass number.  You will notice these numbers usually have a decimal and at least three decimal places to the right.  This is the weighted average of all the known isotopes of that element.  A good example is hydrogen, which normally has only one proton and one electron, zero neutrons.  But there is another form of hydrogen which, in addition to the one proton and electron, has one neutron.  This secondary form of hydrogen is called deuterium.  Another form of hydrogen has the one proton and electron, but also has two neutrons.  This form is called tritium, or heavy hydrogen.

chaobas | Student

In each atom of a substance,the no. of electron and proton are same but the no. of neutrons may vary" These are called as Isotopes.

Let's take an example of carbon which has an atomic number of 6. Carbon has two isotopes viz C-12 nad C-14

Let's find the number of electron. protons and neutrons

Atomic number = number of protons = number of electron

So for C-12 and C-14,

The numebr of protons and electron would be 6 each as they have same atomic number.

And mass number = number of protons + number of neutrons

Numebr of neutrons = mass numeber - number of protons

Now for C-12

Numebr of neutrons = mass numeber - number of protons

=12-6 = 6

Numebr of neutrons  of C-12 is 6

Now for C-14

Numebr of neutrons = mass numeber - number of protons

=14-6 = 8

Numebr of neutrons  of C-14 is 8

So C-12 and C-14 has same number of electron and protons (that is 6 each) but different number of neutrons that is 6 and 8 respectively.

Please try for Uranium By yourself. The isotope of Uranium are U-235 and U-238. And the atomic number is 92