Elements and compounds are pure substances that cannot be broken down physically into a simpler substance. A physical change doesn’t break the bonds between atoms of a substance or form new ones. Compounds can be broken down by a chemical change. A chemical change breaks chemical bonds and/or forms new ones between atoms of a substance. What simple substance would a compound break into? The basic elements that make it up! For example, if you passed a very strong electric current through water you’d break the chemical bonds in water and be left with oxygen and hydrogen. Which of the following is an example of a chemical change?

A
separating water into different glasses

B
breaking frozen ice cubes with a hammer

C
running an electric current through water

D
boiling water to evaporate it on a stove