Isotopes are variants of a particular chemical element which differ in neutron number, although all isotopes of a given element have the same number of protons in each atom. The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. The number of protons within the atom's nucleus is called atomic number and is equal to the number of electrons in the neutral (non-ionized) atom. Each atomic number identifies a specific element, but not the isotope; an atom of a given element may have a wide range in its number of neutrons. The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number.
For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively. The atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that the neutron numbers of these isotopes are 6, 7 and 8 respectively.
And now , I know that I was wrong
You never really cared for me all along
And with you every dream I had
Was all it was , ain't that the fact
So I hold my head deep in my hands
I'm lost at sea no sign of land
I never knew what love could cost
No-one could know how much I've lost
I can't go on now that you've gone
Theres nothing left inside
I'll never understand why you had to lie
It's not enough to say you love
And then just say goodbye
I'll never break these chains
Theres no where to hide
Why did you have to lie?
And now that every hope has gone
I've got to find the strength to carry on
Alone , much more than before
I've given everything , theres nothing more
Why does it hurt so much when theres nothing I can do?
Why do I hate myself 'coz I can't stop loving you?
Now my life is empty
All I have is pain
I can't forget you
Why couldn't you have stayed?