Question

Of what are atoms composed? How do we differentiate them? And what are isotopes?

Answer 1

Where to start....?

Explanation:

Atoms are composed of massive particles, protons and neutrons, that are organized into nuclei, a collection of such particles AROUND which electrons, particles of negligible mass, whizz about. The electrons have an opposite electric charge to the massive, positively charged, nuclear particles, the protons. Exchange of electrons, and sharing of electrons between atoms account for all of chemistry.

And the simplest atom is the hydrogen atom, `""^1H`, the which contains ONE proton, and one electron in the neutral atom. The nucleus could also contain neutrons, of which a given atom could contain various numbers. And this explains the existence of isotopes. And so if an hydrogen nucleus atom contains ONE neutron, in addition to the defining proton, we gots the deuterium isotope...`""^2H`.

And finally to your question. We gots the `""^12C` isotope. Now BY DEFINITION, the element carbon contains 6 protons, i.e. for carbon `Z=6`, within the nucleus there also 6 neutrons...and around the nucleus there are 6 electrons that inhabit various energy levels.

Most carbon nuclei are `""^12C`. A few contain 7 neutrons to give the `""^13C` isotope....and a smaller few contain 8 neutrons to give the `""^14C` isotope.

And please note that if there are 6 positive, nuclear charges, 6 protons, there MUST be 6 NEGATIVE extra-nuclear charges IN THE NEUTRAL ATOM, conceived to whizz about the massive nuclear core. This definition of atomic number and isotopes is a pretty fundamental thing to understand. Keep at it.