The word "氢气球" is formed by sequentially combining the characters for "氢" (hydrogen), "气" (gas), and "球" (ball), where each character contributes a specific semantic component: "氢" specifies the type of gas involved, "气" indicates the gaseous nature, and "球" defines the object as a spherical or balloon-like form, resulting in a compound term that literally means "hydrogen gas ball" or hydrogen balloon.