What are two things that characterize the practice of science

The two things that characterize the practice of science are empirical evidence and community consensus.

That is being able to get the evidence that proves a certain theory, hypothesis or assumption and being neutral in accepting or rejecting the evidence and the results. You should not be biased while drawing conclusions as if this happens, then these conclusions might not be exact or correct.

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom.