Chemical Changes Review

Chemical Changes Review

Unit 1

Matter can not be created or destroyed only changed!

Everything is made of matter, but what is matter made of ?

Atoms

The basic unit of all matter is the atom. Atoms are too small to be seen even with a microscope.

An average person is made up of 7 x 10²⁷ atoms. That is 7 followed by 27 zeros. Most of the atoms that make us up are Hydrogen atoms, oxygen atoms and carbon atoms.

Atomic Theory

1.All substances are made of atoms. Atoms are the smallest particles of matter. They can not be created or destroyed.

2.All atoms of the same element are alike and have the same mass. Atoms of different elements have different masses.

3.Atoms join together to form compounds. A given compound always consists of the same kinds of atoms in the same ration.

Elements

Elements are substances that are made of the same kind of atom. They are all found on the Periodic Table of Elements.

Multiple Select

Do you remember the three elements humans are mostly made of? Check the three that are correct.

• Hydrogen

• Calcium

• Oxygen

• Carbon

Remember, elements are made of the same kind of atom!

Each atom of the substance is the same.

Multiple Select

Check all the substances that are considered elements.

• gold

• water

• oxygen

• carbon dioxide

• silver

Compounds

We have a little less than 100 naturally occurring elements in the universe that we know of BUT we have so many different kinds of matter around us. Elements combine in limitless ways to form Compounds.

Multiple Select

Which of the following are compounds?

• Water

• H₂O

• Sugar

• Hydrogen

• CO₂

Physical Changes

• Matter changes appearance

• Atoms DO NOT REARRANGE

• Change of State - Boiling, Melting, Evaporativng

• Dissolving

Multiple Choice

Which of the following is an example of a physical change?

• mixing baking soda and vinegar causing bubbles to form

• dissolving sugar into sweet tea

• heating sugar until it turns black

• letting milk spoil, forming a solid from a liquid

Chemical Changes

• change in matter where the ATOMS rearrange and

• Form a NEW substance that wasn't there before

Multiple Select

Mark all the examples that result in a chemical change.

• Cooking / Baking

• Boiling Water

• Rusting

• Tearing food with teeth

• mixing food with saliva and enzymes to break it down into glucose

Four Signs of Chemical Change

Gas/Bubbles/Fizzing

Increase/Decrease of Temperature

Change in color

Formation of Precipitate

Multiple Select

Check all the examples of a chemical change.

• Formation of a solid out of a liquid

• fizzing and bubbling after two liquids are mixed

• Salt Dissolving in Hot water

• Food broken down in by saliva in the mouth and acid in the stomach

• Leaves turning brown

And you thought we were finished

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