Chemistry is the science devoted to the study of matter and its composition, structure, and properties. Matter is generally defined as anything that possesses mass and occupies space. Matter can be neither created nor destroyed but can change form, a concept known as the Law of Conservation of Matter.

Matter in its simplest form is called an element. Currently, 118 elements have been identified, each with its own unique chemical and physical properties. Elements combine in specific ratios to form compounds.

Matter can occur in three different states: gas, liquid, or solid. Some compounds and elements occur naturally as solids, some as liquids, and some as gases. Some substances can occur in all three forms and can change from one form to another at specific temperatures. Water is a well-known example of a substance that can occur in all three states. Its most abundant state is as a liquid, but when subjected to temperatures of 0^o Celsius or colder, becomes the solid known as ice. At 100^o Celsius water becomes steam, its gaseous form.

The temperature at which a solid form of matter melts is a quantitative property and differs depending on the matter we are looking at. Below are two time-lapse videos of two different kinds of matter that are transformed to from the solid to liquid state by melting. However, there is a huge difference in temperature required to melt the two different substances. Below, is a video that shows the solid form of water, ice, changing from a solid (ice) to a liquid (liquid water) at temperatures above 0 degrees C. Below the ice-melting video is a video of the melted, liquid form of steel at a temperature of 0ver 1,500 degrees C.

Chemists take advantage of the uniqueness of chemical and physical properties when identifying different substances. Properties can be either qualitative or quantitative. Qualitative properties are those properties that can be used to describe matter but are generally not measured. Qualitative properties include such characteristics as shape, color, state of matter, texture, odor, and magnetism. Quantitative properties are those properties that can be measured. These include but are not limited to mass, volume, length, melting point, boiling point, pH, and density.

Chemists usually rely on a combination of qualitative and quantitative properties when identifying unknown substances. Water and white vinegar are both clear, colorless liquids. Vinegar, however, gives off a characteristic odor that can be used when telling the two compounds apart. Sugar and salt both are white, crystalline solids, but have distinct tastes as well as vastly different melting points. For safety reasons, chemists often do not use odor and taste when identifying unknowns. However, they do make use of other known qualitative properties to help identify substances, as well as to ascertain when new substances form as a result of combining known chemicals.

In this CELL, you will be introduced to chemistry by exploring properties and interactions of matter and you will learn to use the properties of matter such as mass, volume, and pH to identify substances you encounter during your investigations. You will begin your exploration in Investigation One by learning to distinguish between qualitative and quantitative properties of matter and how to determine the quantitative property of mass with a new Procedural Tool, the triple-beam balance.