Eli5. Why is there a limited amount of elements why aren’t there like infinite?

Question

Like what’s stops them at 118?

In: 0

Answer 1

The inside of a heavy atom is made up of “particles” of helium that are being “glued” together by free neutrons stuck in between them.

The amount of force that the bond between two particles of helium and the neutron between them can hold is fixed, but the amount of force being applied to that bond is not. As the atom grows bigger, each free neutron has to hold more and more weight as additional mass is added to it.

Think of it like a chain of people holding hands. If you’re holding hands with one person and they fall down, you only have to be able to support their weight to maintain your grip on them. But if there are 10 people in that chain and they all fall down, now you have to hold the weight of all 10 of those people to keep your grip. The same principle applies to the interior of an atom.

Take Tungsten – that’s made up of 37 helium “particles” and 36 free neutrons. Each of those 36 free neutrons has to support the weight of not just the two heliums that its holding together – but the weight of every other particle in that atom. That’s a total load bearing capacity of ~183 for each neutron to be able to hold the atom together.

Now look at Uranium 238 – that’s made up of 46 helium “particles” and 54 free neutrons. Although there are more neutrons to hold that atom together, that doesn’t decrease the amount of weight that any individual neutron needs to hold, which has now risen to ~237. In other words, each neutron in a Uranium atom is supporting 54 more weight than any given neutron in a Tungsten atom.

If each neutron in that Uranium atom can’t hold a weight of 237, the atom will eventually fall apart.

Since the inside of an atom is a complex 3D structure, there are different ways to arrange the particles inside of it. Some of those arrangements allow for a more equal sharing of weight between the free neutrons than others, and thus are more stable. But at a certain point there just isn’t any way to arrange the inside of an atom in a way to overcome the inherent maximum load bearing capacity of a free neutron.