Chemistry

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Chemistry

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[ Compounds ] [ The Properties of Matter ] [ Periodic Table ]

Everything on Earth is made of matter. Matter comes in three types Liquid, Gas and Solid.

Solid	Liquid	Gas
has a definite shape	takes the shape of its container	has no definite shape
has a definite volume	has a definite volume	has not definite volume( It completely fills whatever container it is in)
difficult to compress	difficult to compress	easy to compress
particles close together vibrate in fixed positions	particles are close together but move freely	particles are far apart

Physical Properties

Chemical Changes

Chemistry is the study of the physical and chemical properties of matter and how they interact with one another. Through the study of chemistry you can learn all sorts of interesting things like How does yeast make bread rise? and How come oil and water don't mix?

The physical properties of a substance can be determined with out any intrusive tests. This means that no test performed with change the identity of the element. You can describe its shape, color, size, weight, height and more without changing the element.

Other types of physical properties are

Thermal Conductivity	ability to transfer heat or thermal energy from one area to another
State	solid, liquid or gas
Malleability	How easy is it to pound into sheets
Ductility	ability to be made into a wire
Solubility	Will it dissolve in another substance
Density	Mass per unit of volume

Density is a very important thing to know sometimes. Density is determined by the following formula.

Density=mass/volume

What's the density of an object with a mass of 50grams and a volume of 3 cu centimeters?

Density=50g/3cu

So now we already have an answer as to why oil floats atop the water instead of mixing with it. They have different densities.

Test this yourself. Take a glass jar and fill it part way with water. Now put some oil in. What happens? If you add more and more oil what will happen?

Although you can easily change the physical properties of an object you don't affect its chemical properties. For instance if you had a piece of paper and kept tearing it into smaller and smaller pieces you would only change its physical properties. The substance would remain paper no matter how many times you tore it.

What other physical changes can you think of?

Chemical Changes

Now a chemical change happens when one or more substances combine or divide to create entirely new substances. Chemical changes are not chemical properties. Chemical changes are the actual change a chemical goes through. Chemical properties tell us a chemical is capable of going through this chemical change. Also some of the Chemical properties of a substance may become clearer based on what kind of chemical change happens.

A common example of a chemical change is when food spoils. When milk sours bacteria have caused a chemical change. It is no longer milk.

In the same way when we bake we combine ingredients that form a product with different chemical properties than any of the individual ingredients.