Chapter 1 and Sections 1 3 Major Goals of Chapter 1
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Chapter 1 and Sections 3.1-3.3 Major Goals of Chapter 1: 1. Define the term chemistry. 2. Identify substances (matter) as chemicals. 3. Describe some physical and chemical properties of matter. 4. Describe the activities that are part of the scientific method. 5. Describe how you tell call whether you have a pure element or a compound. Major Goals of Sections 3.1 - 3.3 1. The organization of matter concept map. 2. Classify matter as pure substances or mixtures. 3. Homogeneous versus heterogeneous substances. Before viewing this powerpoint, go to end of Chapter 1 and read the Chapter Review: 1.1 Chemistry and Chemicals 1.2 Some Fundamental Ideas of Chemistry 1.3 Scientific Method: Think like a Scientist 1.4 A Study Plan for Learning Chemistry Also read, Sections 3.1, 3.2 & 3.3 Classification of Matter They all work to characterize or analyze the composition, structure and properties of matter and the changes that matter undergoes. Creative Chemistry Dr. Gergens - SD Mesa College Chemistry is the study of the composition of matter (substances) and the way in which they interact physically and chemically over time. Energy is involved in every change/transformation of matter. Chemists work to characterize or analyze the composition, structure and properties of matter and the changes that matter undergoes. Section 1.1 - Chemistry & Chemicals Chemistry is the study of the properties of matter. These are: • physical and chemical properties, including, • physical separations and physical changes • chemical separations and chemical changes Matter + Time + Energy + Expert Knowledge Equals New and Useful Substances, Products, and Materials • Chemists work to characterize or analyze the composition, structure and properties of matter and the changes that matter undergoes. • Chemists can use their expert knowledge in designing and performing chemical reactions in the laboratory. • Chemists will even “stir, mix and fish” with the hope of recovering new materials What is matter? A. Matter has and occupies mass . volume a. mass is a physical measurement of the or quantity of a substance. amount Note: the weight of an object depends on the strength of the gravitational force exerted on an object. (weightlessness). b. volume is an area of space for a physical amount of a substance. c. is the ratio of a mass amount per a volume called ; density = mass/volume density Section 1.2 - Some Fundamentals of Chemistry B. Change, ∆ a. physical change in state. For example. boiling liquid water into water as steam b. chemical change is a substance's ability to change form into new some new substance. For example. hydrogen and oxygen react to make water c. a symbol for change is the Greek letter, ∆, delta. C. Time the change in time equals the final time minus initial time This statement would be mathematically written as: ∆t = tfinal - tinitial a. temperature measures the average kinetic energy of molecules. The change in temperature mathematically would be written as: ∆T = Tfinal - Tinitial b. heat energy 1. adding heat, or , is an heat absorbed endothermic process, a change in heat, ∆heat 2. removing heat, or heat released, is an exothermic process, a change in heat, ∆heat 3. The symbol ∆ also represents heat or the process of heating Add these definitions to your “Key Terms” at the end of Chapter 1 ALL PURE SUBSTANCES are HOMOGENEOUS substance - overall composition consists of only one substance. Examples are: pure a. - the fundamental unit of all matter which combines to form compounds. elements b. - two or more elements combined in a fixed ratio or proportion. compounds MIXTURES (impure substances) are two or more different substances mixed together mixtures Mixture Composition Substances as mixtures. There are two types of mixtures: 1. homogeneous For example, a homogeneous solution is a mixture of dissolved solute in a solvent A salt water solution; NaCl ( solute) dissolved in H2O ( solvent) 2. heterogeneous Your eye can see two or more separated phases in the mixture Classic example: vinegar and oil as salad dressing Epsom salt in apricot oil F. Pure Composition homogeneous a. elements - the fundamental unit of all matter which combines to form compounds. b. compounds - two or more different elements combined in fixed a ratio or proportion; having a , for example H2O chemical formula a (molar subscript ratio of atoms) chemical formula H2O (water) 2H:1O 2 hydrogens for every 1 oxygen H2O2 (dihydrogen peroxide) 2H:2O 2 hydrogens for every 2 oxygens Or 1 hydrogen for every 1 oxygen 1H:1O The concept of elements combined in a fixed a ratio A compound has a chemical formula G. Separation of composition 1. Most substances in the universe and on our planet exist as mixtures. Goals of a chemist are to analyze mixture composition and to develop new of techniques for the separation mixture components into pure substances. Section 3.1- Classification of Matter Matter is everything that has density, mass and occupies a volume. Density is the ratio of mass per volume where mass is an amount given in grams and volume is given in milliliters. Matter can be organized into two broad classes; pure or impure. Pure matter, which are elements and compounds, is always homogeneous and has a fixed composition. Impure matter exists as a mixture of substances which can appear either homogeneous or heterogeneous and can have variable compostion. Homogeneous means substance composition is the same throughout. For example, a saline IV solution (salt water) used for IV intraveno therapy to replace electrolytes in a hospital setting. Heterogeneous composition means two or more physically separated phases. For example, oil layered over water. Mixtures can be physically separated into its individual components. Section 3.1- Classification of Matter How do chemists classify whether a sample of matter is either pure or impure by using physical and chemical properties? Pure matter is homogeneous as will be either elemental substance or compound. Impure matter will be a homogenous mixture or a heterogeneous mixture. MOST substances exist as mixtures can be Mixtures separated into individual components. physically thus its composition cannot be physically separated into individual components. Pure matter exists as only one component All pure matter is , as either a pure homogeneous or element . compound If pure matter can be broken down into its chemically elemental components, then the substance is recognized as a . compound Elements cannot be broken down chemically in new elements. II. The Organization of Matter same physical composition throughout two or more physically separated phases Is the composition uniform? Can it be decomposed by ordinary chemical means? Can it be separated by physical means? Section 3.1- Classification of Matter All pure substances are homogeneous Section 3.1- Classification of Matter The concept of isotopes will be discussed at the end of Chapter 3, Section 3.6 Study the physical properties in these box for each physical state. NOTE: Plasma (gaseous hot ions) is our fourth physical state. Classifying all matter into four basic categories a. physical separations b. physical changes c. chemical separations d. chemical changes Chemistry deals with matter, How do chemists classify whether a sample of matter is pure as a compound or as elemental substance or impure as a homogenous mixture, or a heterogeneous mixture, or using the matter organizational chart? Section 3.1- Classification of Matter Memorize this organizational chart III. Separation techniques A. Physical Methods Example, the use of a separatory funnel Paper Chromatography B. Chemical Methods Use of chemical reagents Use of energy to cause a chemical change A. Physical State (s, l, g) & Change,∆ (s) = solid (l) = liquid (g) = gas B. a solution = solute + solvent (aq) = solute dissolved in H2O solvent for example: salt water supplemental HO 8; add symbolisms to your notes melting point temperature boiling point temperature freezing point temperature condensing point temperature Count the total number of atoms on both sides of the arrow. left side right side (reactant side) (product side) Sublimation (going directly from the solid state to the gas state) Dynamic Equilibrium melting and at the same time its freezing boiling at the same time it is condensing Commit these terms to memory Changes in Physical State The melting process is endothermic; heat absorbed The boiling process is endothermic; heat absorbed The freezing process is exothermic; heat released The condensing process is exothermic; heat released supplemental HO 9; add processes to your notes Chemical Change alters the chemical composition of the substance B. What is characteristic about each state? Look over the organizational chart for matter and summarize in your own words the characteristics of a solid, liquid and gas. Note: the fourth state of matter is plasma. Answer theses questions then check your work. In an essay of required length, describe how you would experimentally determine whether a cup of an unknown liquid is: 1) pure water or 2) a sodium chloride water solution or 3) pure ethanol
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