Physical and Chemical Changes

A physical changes happens when ________________

• • the size changes only

• • The size and shape changes only

• • The size, shape or state of matter changes

Why is the breaking of the graham cracker considered a physical change?

• The breaking of the graham cracker involves a chemical reaction that alters its composition.
• The breaking of the graham cracker creates a new substance with different properties.
• The breaking of the graham cracker changes its flavor and aroma permanently.
• The breaking of the graham cracker is considered a physical change because it alters its shape and size without changing its chemical structure.

True or False?

In a physical change, the molecules in a substance stay the same. 

• True - The molecules stay the same.

• False- The molecules do NOT stay the same.

What are the characteristics of a chemical change?

(Pick two answers)

• the remains the same substance

• it cannot be reversed

• the molecules change to something new and a new substance is created

• the atoms remain the same

Why is the burning of the logs considered a chemical change?

• The burning of logs is a physical change as it retains its original form.
• Burning logs creates heat but does not change their chemical structure.
• The combustion of logs is a reversible process that maintains their identity.
• The burning of logs is considered a chemical change because it transforms the logs into new substances through combustion.

All of the following are clues that a chemical change has occurred EXCEPT

• there is a different shape

• light or heat appears

• A gas forms

• a new substance is created

Select 3 examples of chemical changes

• Rust of the car

• A penny that changes colors

• Burning crackers in the fire

• breaking the crackers into smaller pieces

Review: When the form of a substance changes, like the size or shape, a ....................... change has occurred.

• physical
• chemical

When a change causes a new substance to be made, then a ........................... change has occurred.

• chemical

• physical