Sodium atoms combine with chlorine atoms to form sodium chloride (table salt). Which part of Dalton’s atomic theory explains why table salt can be made? Everything is made from atoms and atoms are the smallest unit of matter that can’t be broken down into anything else. Atoms can react together, be separated from each other, or be rearranged via chemical reactions. Atomic nuclei can react in nuclear reactions, which turn matter into energy. Atoms of one element are all the same and are fundamentally different from atoms of other elements.