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

Solid: State of matter with definite shape and volume; particles closely packed and limited movement. Examples: ice, wood, metal. Liquid: State of matter with definite volume but no definite shape; particles less closely packed, allowing flow. Examples: water, oil, blood. Gas: State of matter with no definite shape or volume; particles more spaced out, allowing expansion and compression. Examples: air, hydrogen, oxygen. Pure Substance: Matter with consistent composition and properties; can be an element or compound. Examples: water, gold. Element: Pure substance that cannot be broken down chemically; made of one type of atom. Examples: carbon, oxygen, hydrogen. Compound: Pure substance formed from two or more elements chemically combined; fixed ratio. Examples: water (H2O), carbon dioxide (CO2), table salt (NaCl). Homogeneous Mixture: Substances uniformly mixed and have consistent composition. Examples: air, sugar dissolved in water. Heterogeneous Mixture: Substances not uniformly mixed, different compositions in different parts. Examples: sand and water, oil and water, mixed nuts. Solution: Homogeneous mixture where solute is dissolved in solvent. Examples: saltwater. Chemical Change: Process transforming substances into new substances with different properties; involves rearrangement of atoms/molecules. Examples: burning wood, photosynthesis, rusting iron. Physical Change: Process altering physical properties without changing chemical composition. Examples: melting ice, breaking glass, inflating balloon.