Physical & Chemical Changes

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 boiling, melting, and dissolving.

Front

What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. It involves making or breaking of bonds between atoms. Examples include rusting, burning, and souring of milk.

Front

Is boiling water a physical or chemical change?

Back

Boiling water is a physical change.

Front

What is a compound?

Back

A compound is a substance formed when two or more different elements are chemically bonded together. Examples include water (H2O) and carbon dioxide (CO2).

Front

Are all molecules compounds?

Back

No, not all molecules are compounds. For example, O2 (oxygen) is a molecule but not a compound because it consists of only one type of element.

Front

Which of the following is NOT a physical change: crumpling paper, sharpening a pencil, clothes shrinking, or sour milk?

Back

Sour milk is NOT a physical change; it is a chemical change.

Front

What is the difference between a physical change and a chemical change?

Back

A physical change does not alter the chemical composition of a substance, while a chemical change results in the formation of new substances.

Front

Give an example of a physical change.

Back

An example of a physical change is melting ice into water.

Front

Give an example of a chemical change.

Back

An example of a chemical change is the combustion of wood.

Front

What does it mean for a substance to undergo a chemical reaction?

Back

It means that the substance has changed into one or more different substances, involving the breaking and forming of chemical bonds.