The word "化学键" is formed by combining the characters "化学" meaning "chemistry" and "键" meaning "bond". "化学" itself derives from "化" (change) and "学" (study), referring to the study of changes, while "键" denotes a connection or link. Together, they create a compound term where "化学" specifies the scientific domain and "键" indicates the type of connection, resulting in the meaning "chemical bond".