Physical Science Assessment Probes Answer Key for Is it Matter

When determining whether an object is a solid, liquid, or gas, the most important factor to examine is its molecular structure. Solids have molecules that are tightly packed, limiting their movement. Liquids, on the other hand, have more freedom of movement, allowing them to flow and take the shape of their container. Gases consist of widely spaced molecules that move freely and spread out to fill any available space.

One key element to focus on is the concept of density. A solid typically has a higher density than a liquid, and a liquid is denser than a gas. This relationship helps in understanding the properties and behaviors of different substances when subjected to temperature changes or pressure variations.

To classify a substance, observe its behavior in different conditions. A change in temperature can transform a substance from one phase to another, such as ice melting into water or water turning into steam. These transitions are governed by energy changes, and the temperature at which these changes occur is specific to each substance.