Across
- 2. - The basic building block of all matter in the universe.
- 3. - A group of two or more atoms bonded together that acts as the smallest basic unit of a chemical substance.
Down
- 1. - Something made by combining two or more parts, elements, or words.
- 3. - A physical combination of two or more substances that are mixed together without forming a chemical bond.
- 4. - A fundamental, essential part or component that makes up a larger whole.