The Properties Of Matter

Matter and Changes in Matter

Physical and Chemical Properties Everything around you is some form of

matter. The words that people use to describe

matter describes it’s properties. How would you describe matter?

Properties that are used to identify and classify matter are… Physical Properties Chemical Properties

The words you use to describe how substances look or feel are called a… Physical Property

Here are some examples…

Soft White

Crumbly

Hard

SolidWet

Cool

Rain

Desk

Chalk

Physical Property is …

A characteristic of a substance that can be observed without changing the substance into something else.

They include things like color, density, hardness, melting point, and boiling point.

Chemical Property is…

A characteristic that is observed when a substance changes into a different substance.

Whether a substance burns or doesn’t burn, rusts or doesn’t rust are examples of chemical properties.

Suppose you had 3 samples of metals…

You may notice that they look similar. But, if you could find their melting points ( a physical property), you could tell which was which.

Sodium Iron Tungsten

Suppose you have a beaker of water and a nail… You may see bubbles form on the nail. This is the reaction of the nail to the

hydrogen and oxygen in the water. The resulting chemical would be rust.

The type of reaction that occurs when the nail is put into the water is an example of a chemical property.

Physical Change

Alters the form or appearance of a material but does not convert the material into new substances.

Have you ever noticed steam rising off the hot asphalt after a rain shower?

The water that fell in the form of a liquid is evaporating back into the air as a gas.

The water may change from ice to water to vapor but it is always the same substance.

Chemical Change

A change in matter that forms one or more new substances.

Vinegar and baking soda, when combined, react to form new substances. Bubbles of gas form and the vinegar’s odor disappears.

The key characteristic of a chemical reaction is the production of new materials that are chemically different from the starting materials.

Elements

All the matter around you is made up of more than 100 different substances, called elements.

An element is a substance that cannot be broken down chemically or physically into any other substance.

For example…

Oxygen Tin Calcium Helium

These are all elements and are represented by a one- or two-letter symbol.

O Sn Ca He

Compounds

A substance made up of two or more elements that are chemically bonded together.

If you put two or more letters of the alphabet together, you make a word…

Similarly, elements may be combined to make compounds.

Water

This is one of the most common compounds.

It is formed from 2 parts hydrogen to 1 part oxygen.

A formula shows the ratio of elements in the compound…H2O.

Mixtures

A mixture consists of two or more substances in the same place that are not chemically bonded together.

Most things around you are made up of more than one substance.

For example: Wood, rocks, air, sea water, dust and many foods are mixtures.

Milk

Milk is a mixture that is mostly water, but also contains other substances that give it nutritional value.

These substances include proteins, calcium compounds, and fatty compounds.

Reading Chemical Equations

A chemical equation is a short, simple way to describe a chemical reaction, using symbols and formulas instead of words.

C + O2 = CO2

In words the reaction says, “Carbon reacts with oxygen gas to form carbon dioxide.”

C + O2 = CO2

Carbon (C) and Oxygen (O) are reactants, the substances you start with in a chemical reaction.

Carbon dioxide (CO2) are the products, the substances you end with.

Chemical Reactions on a Small Scale

The matter you see is made up of particles you can’t see.

The smallest particle of an element is an atom. A molecule is a particle made of two or more

atoms. O2 and H2O are molecules. The force that holds the atoms together is called

a chemical bond. During a chemical reaction chemical bonds are either formed or broken. This is how different compounds are formed.