How are atoms created?

Question

I'm a little new to the subject but does the fact that the universe is expanding means more and more atoms are being created?

I'll be grateful if you explain yourself in an accessible way. Thank you.

Answer 1

No new matter is being created. The universe is expanding because everything is still flying outwards from the big bang.

All the matter in the universe was created in the first moments after the big bang when pure energy condensed into matter and antimatter. Most of the matter and antimatter collided and was converted back to energy, but for reasons too complicated to go into here slightly more matter than antimatter was created, so there was a "little bit" of matter left over. That was hydrogen, and from it were created all the stars and galaxies that we can see around us.

New atoms are being created inside stars, where hydrogen and helium atoms are converted into heavier elements like carbon and oxygen. This uses up hydrogen and helium atoms so the universe is actually losing atoms.