Simplify the following text for a Grade 10 native English-speaking person.
Original: A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions . Chemical compounds have a unique and defined chemical structure ; they consist of a fixed ratio of atoms that are held together in a defined spatial arrangement by chemical bonds .
Simplified: A chemical compound is a chemical made by joining together atoms of different chemical elements .