This question is essentially asking what would happen if there were no chemical reactions. The short answer is, not much. Not in the sense that little would change from the way the universe exists currently, but rather that far less would happen if atoms did not gain and lose electrons. All materials are made of chemicals, and chemical reactions are responsible for every change that produces a new material, and chemical reactions more or less are the gaining and losing of electrons ( to form bonds ). (Note that this is different from phase changes (examples of physical changes), such as melting, wherein a material retains a chemical makeup but changes from solid to liquid.) C. If atoms did not gain or lose electrons, photosynthesis would not be possible, so there would be far less oxygen for living organisms to breathe, cells could not perform cellular respiration, meaning they could not produce ATP for energy to do anything (not that the cells to perform that respiration could form anyway), nothing could be burned for cooking or power generation, metals would not rust (I suppose not such a bad thing), there would be no plastics, no paper to write on, ...

Essentially, gaining and losing electrons (i.e., participating in chemical reactions) is necessary for life as it exists on Earth today.

If all the atoms didn't need to gain or lose electrons, there would be no chemistry, which means no molecules, no compounds, no non-gas substances, and no life.

The reason atoms gain and lose electrons is because that's what they want to do. They aren't happy or unhappy, but they like to come together in some ways and not others. It's like magnets that like to come together with their North poles all pointing the same way, but they push each other apart if you put 2 North poles facing each other. Atoms do something like that, at tiny, tiny sizes.