A biological species can be defined as the concept which includes the group of individual which lives in one or more population that can reproduce among each other to produce viable species.
Speciation is the phenomenon by which one group of species gets separated from another. The species gets diverge due to reproductive isolation or due to geographical isolation.
Since it says all carbon atoms have six electrons, we know that they only have six protons too. The carbon 13 and 14 means they have extra neutrons that increases their atomic mass.
