Characteristics of Materials
Everything on earth is made up of matter, including the earth and including ourselves. Matter is defined as anything that has mass and occupies space. Look around you, notice that everything has mass and occupies a certain space. Even the invisible air you're breathing has this property! Because everything is made up of matter, it is very important that we study it and how it behaves. A part of studying matter is understanding its characteristics or its structure and properties.
Matter can be divided into two groups. The first group classifies matter in terms of its physical state. We know these states as solid, liquid and gas. The second group classifies matter in terms of its compositionand properties, as elements, compounds, and mixtures. Take note that any kind of matter found in its pure form (no matter what state) and is uniform throughout its composition (unchanging all throughout) is called a substance.
The objects or materials that surround us come in different states of matter, and are in this state due to intermolecular forces. This means that matter is held together by the forces found between its molecules. For example, water is made up of H2O molecules. These molecules stick to each other or attract each other through electrons. As a result we don't see the molecules, instead we see all the molecules joined together to make water.
In solids, intermolecular forces are very strong. They join the material together so well that it becomes a solid. In liquids, the forces are slightly weaker, allowing the matter to flow or have movement within itself, but the forces are still strong enough to hold the matter or liquid together. Gases have the weakest intermolecular forces between them. This is how they can float freely around and occupy any space.
We know from our other lessons that liquid can turn into solid (water to ice), solid can turn into liquid (ice to water), liquid can turn into gas (water to air), and solid can turn into gas (dry ice.) However, did you know that when liquid evaporates, it can leave behind material that does not evaporate? If a solid material was mixed into a liquid, when the liquid turns into gas, it leaves behind the solid substance.
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