chemistryとは何ですか？ chemistryとは何ですか？ The science of the composition, structure, properties, and reactions of matter, especially of atomic and molecular systems.The composition, structure, properties, and reactions of a substance.The elements of a complex entity and their dynamic interrelation: "Now that they had a leader, a restless chemistry possessed the group” ( John Updike). Mutual attraction or sympathy; rapport: The chemistry was good between the partners.