To introduce or mix a substance into an otherwise pure substance to pollute.

When a pure substance has impurities introduced into it.

Impurities in a substance.

Any solid materials dissolved in water, typically while the water is in contact with earth materials. Dissolved solids are commonly metal ions like calcium, sodium, and magnesium.

Water that has been heated and recondensed to drive off mineral impurities. Distilled water may have a slightly acidic pH.

Water that comes from an underground spring or comes out of the ground on its own and is bottled.

Living (or once-living) organisms, including bacteria, viruses, and parasites, present in groundwater, surface water, land, or the atmosphere.

Chemicals such as fertilizers, gasoline, oil, heavy metals, or acids are introduced into groundwater, surface water, land, or the atmosphere.

A disease carried by water, such as cholera.

Any chemical or biological substance that pollutes water.

When water is polluted by chemical or biological substances.

Contamination by chemical or biological substances that make water unsafe for living things.

A state of matter where the atoms or molecules are farther apart than in a liquid and moving faster than in a liquid.

A state of matter where the atoms or molecules are packed less closely than a solid but more closely than a gas and moving more than a solid.

Atoms or molecules of a substance. All matter is made of particles that are in constant motion. Atoms are the building blocks of matter. Two or more similar or dissimilar atoms can combine to form a molecule.

A homogeneous state of matter, solid, gas, or liquid.

A physical change occurs when a substance changes its state from a solid to a liquid (melting), a liquid to a gas (boiling, evaporating), a solid to a gas (sublimation), a gas to a liquid (condensing), or a liquid to a solid (freezing). A physical change also occurs when a material is broken into smaller pieces or combined into larger ones.

A characteristic of a substance or material, such as color, density, flexibility, and hardness. These properties help identify pure substances and never change whether there is a large or very small sample of material. They are intrinsic properties.

Description, observation, or analysis of a substance based on measurements.

Description, observation, or analysis of a substance based on its qualities.

A state of matter where the atoms or molecules are packed closely together and do not move freely.

Anything that has mass and takes up space.

The gas phase of a substance.

A variable in an investigation or experiment that is held constant.

The observed phenomenon that is being measured.

To break down into smaller particles. For example, a solute (like sugar) dissolves into a solvent (like water) to form a solution.

The controlled variable in an experiment.

When the maximum amount of a substance—a solute—has dissolved in a solvent.

When a solvent has had the maximum amount of a substance—a solute—dissolved into it, and not more can dissolve.

A solute that can dissolve in a solvent, a liquid or a gas.

A substance that cannot dissolve in a particular solvent.

The substance dissolved when a solution is formed. For example, in a salt-in-water solution, the salt is the solute.

The liquid in which a substance is dissolved when a solution is formed. For example, water is the solvent in a salt-in-water solution.

A mixture of one or more substances in water forms a clear liquid that may be colored or colorless.