Assistant Laboratory Animal Technician (ALAT) Practice Exam

What is a molecule?

1. One atom

2. Two or more atoms bonded together

3. A single compound

4. A chemical reaction

The correct answer is: Two or more atoms bonded together

A molecule is defined as two or more atoms that are chemically bonded together, forming a distinct and stable unit. This bonding can occur between atoms of the same element, such as in oxygen gas (O2), or between different elements, such as in water (H2O). Molecules can be simple, like diatomic molecules, or complex, like large biological macromolecules. The other options don't accurately capture the definition of a molecule. An individual atom represents a single unit and cannot be considered a molecule by itself. A single compound generally refers to a pure substance made up of molecules, but the term "compound" doesn't specifically address the bonded nature of the atoms. Lastly, a chemical reaction describes the process by which substances transform into new products and does not define what a molecule is. Therefore, the characterization of a molecule as two or more atoms bonded together is the most accurate and comprehensive description.