Bioenvironmental Engineering Apprentice (BEA) Block 2 Practice Test

The key idea is how we classify matter by whether its components are chemically bonded and whether the mix is uniform. A heterogeneous mixture is made of two or more pure substances that keep their own identities and are not chemically bound to each other. Because the components aren’t chemically fused, you can usually see or separate them using physical means like picking apart, filtering, or decanting. That’s why this term fits best for a substance that contains different substances each retaining its own properties, such as a bowl of trail mix or granite with visibly different minerals. Elements are single kinds of atoms, so they don’t describe a combination of different substances. Compounds are two or more elements chemically bonded into a new substance with a distinct composition. Solutions are homogeneous mixtures where the components are uniformly distributed at the molecular level, so you can’t distinguish them.