system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5 what is anti matter?
gpt
Antimatter is exactly the same as normal matter, just "opposite". Normal hydrogen for example is composed of a proton and an electron, with the proton being positively charged and the electron being negatively charged.

For antimatter the positively charged proton would be replaced by a negatively charged antiproton. Same mass, same strength of charge, just flipped. The negatively charged electron would also be replaced by a positively charged positron. Again identical to an electron except with opposite charge.

Antimatter seems to behave exactly the same as normal matter we are familiar with, at least as far as we can tell. This means we would expect all the same elements to be made, and even chemical reactions to work the same with antimatter. Of course we can't test this very well because handling antimatter is very difficult since if it encounters normal matter they annihilate each other and release huge amounts of energy. Making antimatter is very difficult and can only be produced in small quantities so the testing we can do so far is limited.

And yes, it is a bit strange that matter is the way it is and not the flipped antimatter version. Scientists are still trying to figure out why the universe seems biased towards one kind (the one we are familiar with).