Understanding the difference between Physical and Chemical changes

Class, here are more notes to help you understand the difference

between Physical and Chemical changes. 

•Physical changes:

1)Appearance can change, but substance keeps the same identity.

2)You can always go back to the original substance.

•Chemical changes:

1)Substance formed is new. New molecular arrangement.

2)You can not go back to the original substance (not reversible). 

This This is another way of thinking about the differences:

During a chemical change, there is a change in the chemical composition of the original molecules. New elements or compounds form at the end, with a different arrangement of atoms. Bonds break and reform! But in a physical change the molecules stay the same, they just move farther apart or closer. Look at the picture below to see the differences: 

(notice how the arrangement of atoms changed when water became hydrogen peroxide)

Here are videos to help you understand the differences
too. Click on here- 
BrainPop- Property Changes



Also, click on here to watch several videos- 
Physical and Chemical changes

Remember these 2 important concepts:

The Law of Conservation of Mass:

During a chemical reaction, the mass of what you end with is
always the same as the mass of what you start with.

 Chemical reaction:

occurs when you start with one molecule and turn 

it into a new one. Chemical bonds are made or 

broken in order to create this new molecule. 

Finally, here is a great article that details the difference between both types of changes- The Ice-Cube Tray and the Frying Pan