 One of the important things that we do need to briefly touch on is an idea around fragmentation Because sometimes with particularly long molecules when they're undergoing this process in order to have their mass measured Parts of them can break off. So if we look at probably one of the simplest examples of this Say we were trying to Find the mass spectra for ethane It would be really nice if we could charge up this little ethane molecule so that it was then accelerated Put through a magnetic field which would bend its path and then we could identify it and we would say okay. There's 12 twos as there's two carbons and there's six ones Which is hydrogen so we would expect to have a mass of around about 30 Atomic mass units as this comes scooting through And that would to give us the data assuming there were no isotopes of hydrogen other than hydrogen one No isotopes of carbon other than carbon 12 and also at no the electron That's creating the charge is not contributed to the mass in any way and also that the frag that the whole of the Molecule remained intact all the way along. So what we'd see is just one beautiful nice peak at 30 and nothing else In reality, this does not happen It doesn't happen for several reasons one because isotopes do exist and therefore there may well be a Little mini peak on 31 for example where a carbon 13 may be present or even a hydrogen 2 But the other thing that can happen is that this molecule can fragment and if it fragments that means it basically snaps somewhere And the simplest place for it to snap is right down the center And if it snapped right in the center then we now have two fragments both of which have one carbon With a mass of 12 and three hydrogens with a mass of one so 12 plus three ones is 15 so that would mean instead of having a peak at 30 we would have a Lower peak at 30 and another peak here at 15 Where some of the molecules have traveled through the mass spec intact and to come out the other end with their full 30 atomic mass units intact Whereas others would have been split in half and so you'd only have Little of fragments which would be deflected more because that experienced greater acceleration and therefore We'd have a peak at 15 as well So this is one of the reasons when we're looking at the output data from mass spectroscopy We we notice that there is going to be a maximum value that maximum value is going to tell us the molar mass of the molecule If there are no isotopes it will tell you exactly what the identity is perhaps But again, you still need other data to look at that Because this is just giving you information about masses What's nice is if we get fragment data as well and we start to know that for example a CH3 group has a mass of 15 then either we can look for peaks at 15 or we can even look at Fragments that are 15 less than the total mass of the Molecule intact molecule to know that a CH3 group has been cracked off at at some point