Unit 1 8th grade Review 2025

Front

What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting, freezing, and dissolving.

Front

What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. Examples include rusting, burning, and digestion.

Front

Which type of change is most often easily reversed?

Back

Physical change.

Front

What is the difference between a compound and a molecule?

Back

Every compound is a molecule made up of two or more different elements, but not every molecule is a compound; some molecules consist of only one type of element.

Front

What is a mixture?

Back

A mixture is a combination of two or more substances that are not chemically bonded. The individual components retain their own properties.

Front

What is an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen, oxygen, and gold.

Front

What is a solution?

Back

A solution is a homogeneous mixture where one substance (the solute) is dissolved in another (the solvent). An example is sugar dissolved in water.

Front

What is a particle diagram?

Back

A particle diagram visually represents the arrangement and behavior of particles in a substance, helping to illustrate whether it is an element, compound, or mixture.

Front

What is the law of conservation of mass?

Back

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction; it is conserved.

Front

What is a homogeneous mixture?

Back

A homogeneous mixture is a mixture that has a uniform composition throughout, such as saltwater or air.