Matter

What is matter?

Moira Whitehouse PhD

Matter includes everything around us--• our couch, our bed, our computer

• our food and our drinks• our family and our dog or cat

• the grass and the trees

• the Sun and the Moon

• all the planets• everything in our Universe

Yes!

Everything

Everything

Everything

Matter on Earth is usually in one of three states.

solids

• Keep their shape unless they are broken

• Do not flow or pour

We know when matter is a solid because solids:

liquids

We can tell when matter is a liquid because liquids:

• Do not keep their own shape; they take the shape of the container they are in.

And...liquids flow or pour.

Oil being poured on a salad

Then what about sand, sugar and salt? Don’t they pour, flow and take the shape of the container they are in?

If you magnify sand or sugar, you can see that they are not liquids. Sand, salt, and sugar are made up of very small particles that have a definite shape .

Child blowing air (a gas) into a balloon.

gasThen there is that third state of matter:

A balloon or a bubble are just containers that hold a gas. For us that gas is usually air.

There are other gases besides those in air. These balloons contain a gas called helium which is lighter than air.

Air, like all gases, takes the shape of its containerand expands to fill its container.

Most gases including the gases in air are invisible—you simply cannot seem them.

A jar of air

However, you do know air is there when it moves things such as this windmill.

Wind—moving air– causes this windmill to rotate.

Or when you use the gas in your lungs to blow out a candle.

But air is not one gas; it is a mixture of many different gases—mainly nitrogen and oxygen plus a little carbon dioxide, argon and water vapor.

not one

mixture

This pie chart shows the many gases that go together to make up air.

Gases are hard to observe because remember, we said that most are invisible.

Most gases have no color, no taste, no smell and you cannot feel them unless they move.

Because all these gases are invisible we cannot tell one from the other just by looking at them or smelling them.

Jar of carbon dioxide

Jar of nitrogen

Jar of oxygen

If you did not have any oxygen for more than a few minutes you would die!

Without the very tiny bit of carbon dioxide in the air, there would be no green plants. Plants use carbon dioxide to make food.

Oxygen is also needed for things to burn. Without oxygen nothing burns.

Although most of air is nitrogen, nitrogen gas doesn’t do very much all.

But they are all very different gases.

Things burn much more quickly in pure oxygen than in air. Air contains about 20 percent oxygen.

Velcro burning in air smokes and smells but doesn’t burn much, because air is only 20 percent oxygen.

Velcro with pure oxygen erupts in flame.

Another common gas is Carbon Dioxide. We learned in the last slide that Oxygen is necessary for things to burn. Carbon Dioxide, on the other hand, puts fire out.

Carbon dioxide gas reacts with a substance called bromophenol blue changing it from a blue color to yellow. To show that your breath has Carbon dioxide, blow into a bromophenol solution.

Students exhaled through a straw into the bromophenol blue. The carbon dioxide in their breath changed the color to yellow.

Making carbon dioxide in a ziploc bag

Teachers, creating Carbon Dioxide in the ziploc bag allows students to see that there is something there pushing the sides of the bag out. The gas fills its container and takes the shape of its container, and it is invisible. If you insert a burning match or glowing splint into the bag, students will see that this gas puts fire out.

Particles in a solid

Particles in a liquid

Particles in a gas

Later on you will learn that movement of the tiny particles that make up matter determines if the matter is a solid, a liquid or a gas.

Can you name the three states of matter?

Bubbles hold an invisible gas called water vapor

Can you tell the difference between these three states?