Explain how chemical changes involve making and/or breaking chemical bonds

A chemical change occurs when reactants undergo molecular or ionic rearrangements of atoms to form new substances. This is facilitated by the breakage of bonds which require consumption of energy and making of bonds which release energy.

For instance, when sodium reacts with water there is a vigorous reaction that produces sodium hydroxide NaOH and hydrogen gas ()

Clearly the molecules of bonds are broken to make bonds with Na and form NaOH and H₂.

Another example

In this case hydrogen peroxide gets broken down

to form water and oxygen

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.