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C HAPTER 1: M ATTER AND C HANGE Chemistry 1-2 Mr. Chumbley.

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Presentation on theme: "C HAPTER 1: M ATTER AND C HANGE Chemistry 1-2 Mr. Chumbley."— Presentation transcript:

1 C HAPTER 1: M ATTER AND C HANGE Chemistry 1-2 Mr. Chumbley


3 W HAT IS C HEMISTRY ? For most of human history, the natural sciences were divided into two broad categories: Biological Sciences Physical Sciences However, those divisions began to break down as knowledge increased Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes

4 B RANCHES OF C HEMISTRY As the understanding of matter and its processes increased, different branches of chemistry arose to better describe specific types of chemicals and processes A chemical is any substance that has a definite composition Organic ChemistryInorganic Chemistry Physical ChemistryAnalytical Chemistry BiochemistryTheoretical Chemistry

5 C HEMISTRY A PPLICATIONS Basic chemical research is conducted for the purpose of expanding knowledge Applied chemical research is conducted for the purpose of solving a specific problem Technological development involves the production and use of products to improve the quality of life

6 H OMEWORK Read: Chapter 1, Sections 2: Matter and Its Properties Stop once you get to “Main Idea: Matter can be a pure substance or a mixture.”


8 W HAT IS M ATTER ? It is much easier to identify that things are made up of matter than it is to define matter By looking at the same properties for all matter there are two universal commonalities: Things made of matter take up space (have volume) Things made of matter have mass Mass is a measure of the amount of matter Using these universal characteristics we can define matter Matter is anything that has mass and takes up space

9 A TOMS ARE THE BUILDING BLOCKS OF M ATTER While matter exists in many different forms, the most fundamental form is the atom An atom is the smallest unit of an element that maintains the chemical identity of that element An element is a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom

10 A TOMS ARE THE B UILDING B LOCKS OF M ATTER When atoms of different elements chemically combine, molecules of a compound are formed A compound is a substance that can be broken down into simple stable substances, but is made from the atoms of two or more elements that are chemically bonded The smallest unit of a compound is a molecule

11 A LL S UBSTANCES H AVE C HARACTERISTIC P ROPERTIES The specific characteristics of a substance, either element or compound, are considered its properties Properties can be used to identify individual substances, or an entire group of substances Properties can be one of two types Extensive properties depend on the amount of matter present mass volume total energy Intensive properties do not depend on the amount of matter present melting point boiling point density conductivity

12 P HYSICAL P ROPERTIES Properties of substances are often used as identifying characteristics Physical properties are characteristics that can be observed or measured without changing the identity of the substance Examples: masscolorshape densityvolumetexture boiling pointmelting pointconductivity

13 P HYSICAL C HANGES The physical properties of a substance are can change, even if the substance does not A physical change is a change in a substance that does not involve a change in the identity of the substance Examples: cuttinggrindingpolishing boilingmeltingdissolving

14 S TATES OF M ATTER Matter exists in states of matter that are physical properties When a substance undergoes a change of state, it is a physical change from one state to another While the substance has some new and different physical properties, the chemical identity has not changed

15 S TATES OF M ATTER State of Matter Definite Shape Definite Volume SolidYes LiquidNoYes GasNo As a substance changes from solid to liquid to gas, the atoms or molecules become less organized and have increasing ability to move away from each other A fourth state of matter, plasma, is a high- temperature physical state of matter in which atoms lose most of their electrons

16 C HEMICAL P ROPERTIES In any situation where a substance could change its identity, chemical properties can be observed Chemical properties relate to a substances ability to undergo changes that transform it into a different substance Examples: reactivity chemical stability flammability toxicitycombustibilityradioactivity

17 C HEMICAL C HANGES A chemical change (or chemical reaction ) is a change in which one or more substances are converted into different substances The reactants are the substances that react in a chemical change The products are the substances that are formed by the chemical change

18 S IGNS OF A C HEMICAL C HANGE Production of an odor Change in temperature Change in color Formation of bubbles Formation of a solid Emission of light

19 E NERGY AND C HANGES IN M ATTER In both physical and chemical changes, energy is involved Many different types of energy can be involved The law of conservation of energy says that energy can be absorbed or released, but it is never created nor destroyed

20 H OMEWORK Read: Chapter 1, Sections 2: Matter and Its Properties Start at “Main Idea: Matter can be a pure substance or a mixture.” Finish at the end of Section 2 Answer #1-5 of the Formative Assessment on p. 14

21 M ATTER C AN BE A P URE S UBSTANCE OR A M IXTURE The variety of forms in which matter can exist is enormous Two major classifications of matter are whether or not it is a pure substance or a mixture Regardless of whether a sample is a pure substance or a mixture, it can be described and classified in terms of its properties

22 P URE SUBSTANCES A pure substance is any form of matter that has a fixed, or definite, composition Pure substances have two defining characteristics: Every sample of a given pure substance has exactly the same characteristic properties. Every sample of a pure substance has exactly the same composition.

23 M IXTURES A mixture is a blend of two or more kinds of matter each of which retains its own identity and properties Another way of describing a mixture is that the matter combines physically, but not chemically Since mixtures do not have a defined composition, the amount of different substances within a sample of a mixture must be specified

24 M IXTURES Mixtures can be described by the uniformity of their compostion Homogeneous mixtures (or solutions ) are mixtures that are uniform in composition Heterogeneous mixtures are mixtures that are not uniform in composition

25 M IXTURES One of the most important characteristics of a mixture is that it can be physically separated Examples of physical separation: Filtration Vaporization Settling Centrifuge separation Chromatography

26 L ABORATORY C HEMICALS AND P URITY Typically, we treat chemicals used in the laboratory is if they were pure Chemicals do have impurity, and depending on the standards and grade desired or used The level of purity is important to know since the level of impurities can affect results

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