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Properties of Matter Help (page 2)

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By — McGraw-Hill Professional
Updated on Aug 28, 2011

Solids, Liquids, And Gases

Chemistry and the study of matter focus on the forms of matter. Scientists describe the three basic forms of matter as: solid, liquid , and gas . Figure 3.2 illustrates these three different forms that matter can take.

Properties of Matter Solids, Liquids, And Gases

Fig. 3.2. The three forms of matter consist of solids, liquids, and gases.

Solids include things like boulders, metals, crystals, and glass. They are fixed in shape and rigid with a measurable volume. To change shape in a major way, a strong outside force like fire or heavy impact is needed.

Liquids such as water, oil, and alcohol have been known for centuries. They have a measurable volume, but are bendable and can change shape. Liquids are easier to study since they fill the shape of their container and flow from one place to another. They do not require force to change shape, but are affected by heat.

Gases are a different story. They have neither form nor volume and expand to fill the entire container into which they are placed. At times they are visible and then disappear. They seem to come from nothing and leave to go nowhere. Ancient alchemists’ ideas of transmutation seem to better describe the mystery of gases.

To make things even more interesting, some liquids like water can take on all three modes (water, ice, and steam) at different times. Scientists wanted to understand how this happened. Through much experimentation, it was discovered that matter had specific properties .

Properties

The unique character or the way an element reacts is said to be its properties . These properties are grouped into two classes, physical and chemical .

Physical properties are special characteristics that make up the physical composition of a sample. Physical properties include: color, form, density, thermal and electrical conductivity, and melting and boiling points. Physical properties can be seen without any change in form or dimension. For example, barium is commonly silvery white in color, a solid, melts at 727°C (1341 °F) and burns green at a wavelength of 554 nanometers. Even melted, it is still barium, but in a different form than when it was solid.

Chemical properties are those characteristics that focus on a substance’s behavior when mixed with another element or compound. For example, copper when exposed to oxygen turns green on the surface, but doesn’t dissolve in water. The reaction that causes the surface to turn green forms a very thin layer (copper carbonate or copper sulfate) that actually protects the surface from further corrosion.

Iron is abundant in the Earth’s crust and was one of the first refined metals. However, it is never found in its pure form, but as an oxide (combined with oxygen). Iron chemically reacts with air and water to form rust, a porous crumbling material that sticks loosely to the iron’s surface. When rust crumbles and falls away, a new place on the iron’s surface is exposed; eventually the entire sample will rust away.

 

Practice problems for these concepts can be found at - Properties of Matter Practice Test

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