Q2Q Binding energy question (1 Viewer)

[porcupinetree]

I'm a little bit confused about the binding energy per nucleon graph - I understand that a greater BE/A results in a more stable nucleus, However, what I'm confused about is fusion and fission, and why they release energy. For example, if Uranium splits to form products with an overall higher binding energy, then why is energy released, if we've gone from a lower energy state to a higher energy state?
I've read explanations that explain binding energy as a sort of 'glue' that binds a nucleus together - when nucleons come together, some of their mass is converted to glue. Using this analogy, when Uranium splits, the total glue of the products is more than the reactants. Thus some of the mass of the Uranium nucleons has been converted into the glue of the products.
If so, then where does any extra energy come from? As I see it, the transition from Uranium --> Barium + Krypton shouldn't release any energy; all that should happen is that some of the mass of the reactant is converted into the binding energy of the products.

Can someone please try to explain? Thanks

 

[BOS Secret Service]

All comes down to the mass defect. Mass is not conserved.

 

[mrpotatoed]

Iron has the highest binding energy. Anything to either side of it (in a binding energy graph) has less binding energy per nucleon. When you have elements to the right of iron, fission releases energy, and fusion absorbs energy (this is because in fission, the products have a higher binding energy, and so energy is released to put them deeper in the potential well). To the left of iron, fission absorbs energy and fusion releases energy (this is because in fusion, the products have a higher binding energy, and so energy is released to put them deeper in the potential well).