Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: assigned a unique one-, two-, or three-letter symbol. The names of the elements are listed in the periodic table, along with their symbols, atomic numbers, and atomic masses. The chemistry of each element is determined by its number of protons and electrons. In a neutral atom, the number of electrons equals the number of protons. Answer: protons and electrons
A:
The chemistry of each element is determined by its number of what?