What would need to happen for silver to become gold? Such as, if two silver smashed together in nuclear fusion, could that form a gold atom, with pieces left over, or would it become another element?
Also, when that happened, what would be the energy and situational requirements for this to happen? And would it change based on the different elements used/created?
Well, the short answer is YES, it can (theoretically) be done. BUT, it would cost a LOT more than the final product (gold) produced! Silver (Ag) has a mass of 107.9 g/mol, and gold (Au) is 197 g/mol. So whatever elements you'd like to start with, it would need to fuse with silver to add an additional 90 g/mol in the form of an additional 32 protons and electrons per atom.
However, the energy required (and initial cost, if starting with silver!) to effect the fusion would cost much more than the resulting gold would be worth. IF "wealth" is a goal, I would suggest that anyone who could find a way to produce the necessary energy at an economic cost would get wealthy much faster by selling that energy than manufacturing gold!
Note that the "elements" are defined by their atomic structure, so changing any part of any one also changes the "element".
Thank you. However I would like to clarify that this is not for wealth, but to put energy consumption in a game into perspective. Could I combine multiple elements at once with silver to make the gold? Also, how much energy is required?
It's really not quite that simple, so for any game use, make up what you like. In reality we can't just bump elements together and hope they stick like Lego blocks. The buildup is by neutron bombardment followed by natural decay processes for the most part. Using 'realistic' technology it is a LONG road from silver to gold! Here are a couple of references than may provide both the perspective, and possibly some values for your purposes.