how do we know isotopes exist?

Question

schrodinger · Answer

We observe them? I'm not sure what you mean, we see isotopes all the time, we are sure they exist.

jfraser · Answer

we know isotopes exist because we "see" them separate using a mass spectrometer. If only 1 kind of element existed, when we perform this experiment, we'd see one big pile of atoms all being deflected by the same amount. Since the masses of isotopes are all different, they are all deflected by slightly different amounts, creating different "piles" of the isotopes that element has.

anonymous · Answer

mass spectrometers are why we know... they are a device used to measure the mass of an atom by telling it apart from another atom. put carbon in the machine and you will get 2 pulses, one for each form of carbon. therefore there must be 2 carbons with different masses. we named it carbon 12, and the on with the lower pulse (by far), carbon 14.