Define the following terms: solid, liquid, gas, pure substance, element, compound, homogeneous mixture, heterogeneous mixture, solution, chemical change, physical change.

Solid: A state of matter with fixed shape and volume, characterized by closely packed particles with limited movement. Liquid: A state of matter with fixed volume but not shape, where particles flow and take the shape of their container. Gas: A state of matter with neither fixed shape nor volume, where particles are widely spaced and occupy the entire volume of the container. Pure substance: A material composed of only one type of particle, either an element or a compound, with consistent properties and fixed composition. Element: A pure substance that cannot be broken down further; basic building blocks of all matter, represented by symbols in the periodic table. Compound: A pure substance formed by the chemical combination of two or more elements in a fixed proportion, having properties different from their constituent elements. Homogeneous mixture: A mixture with evenly distributed components, giving it a uniform appearance. Solutions are a type of homogeneous mixture. Heterogeneous mixture: A mixture with unevenly distributed components and visibly distinguishable components, e.g., oil and water. Solution: A type of homogeneous mixture in which solutes are uniformly distributed within a solvent. Chemical change: A process converting substances into new substances with different properties through the breaking and forming of chemical bonds. Physical change: A change in size, shape, or state of matter without altering chemical composition, e.g., melting ice.