Final - Section 1.1 Chemistry is the study of the...

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Section 1.1 Chemistry is the study of the composition, structure, properties, and changes of matter . The composition of matter relates to the kinds of elements it contains. The structure of matter relates to the ways the atoms of these elements are arranged. A property is any characteristic that gives a sample of matter its unique identity. A molecule is an entity composed of two or more atoms with the atoms attached to one another in a specific way . Section 1.2 Matter exists in three physical states, gas , liquid , and solid , which are known as the states of matter . There are two kinds of pure substances : elements and compounds . Each element has a single kind of atom and is represented by a chemical symbol consisting of one or two letters, with the first letter capitalized. Compounds are composed of two or more elements joined chemically. The law of constant composition, also called the law of definite proportions , states that the elemental composition of a pure compound is always the same. Most matter consists of a mixture of substances. Mixtures have variable compositions and can be either homogeneous or heterogeneous; homogeneous mixtures are called solutions . Section 1.3 Each substance has a unique set of physical properties and chemical properties that can be used to identify it. During a physical change , matter does not change its composition. Changes of state are physical changes. In a chemical change (chemical reaction) a substance is transformed into a chemically different substance. Intensive properties are independent of the amount of matter examined and are used to identify substances. Extensive properties relate to the amount of substance present. Differences in physical and chemical properties are used to separate substances. [An extensive property is a property that changes when the size of the sample changes. Examples are mass, volume, length, and total charge. An intensive property doesn't change when you take away some of the sample. Examples are temperature, color, hardness, melting point, boiling point, pressure, molecular weight, and density. Because intensive properties are sometimes characteristic of a particular material, they can be helpful as clues in identifying unknown substances.] The scientific method is a dynamic process used to answer questions about our physical world. Observations and experiments lead to scientific laws , general rules that summarize how nature behaves. Observations also lead to tentative explanations or hypotheses . As a hypothesis is tested and refined, a theory may be developed. Section 1.4 Measurements in chemistry are made using the metric (e ) system . Special emphasis is placed on a particular set of metric units called SI units ( ) , which are based on the meter, the kilogram, and the second as the basic units of length, mass , and time, respectively. The metric system employs a set of prefixes to indicate decimal fractions or multiples of the base units. The SI temperature scale is the
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This note was uploaded on 01/18/2009 for the course CHM 120 taught by Professor Pande during the Spring '08 term at SUNY Albany.

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Final - Section 1.1 Chemistry is the study of the...

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