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Download Chapter 1 Chemistry: The Study of Matter
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Chemistry Enriched 1 Chapters 1-3 Matter and Change 2 Demonstration: Burning Candle What is happening? 3 Objectives: Describe the difference between a physical change and a chemical change and give several examples of each. Describe different characteristics of the three states matter. Classify a mixture as homogeneous or heterogeneous. Classify a pure substance as an element or a compound. Identify methods of separations of mixtures. State the laws of conservation of mass and energy. 4 Chapter 1 Chemistry is a Physical Science 5 Chemistry is the study of matter and the changes it undergoes. Biological Science Chemistry Physical Sciences Chemistry is central to all sciences. Both living and non living matter have a chemical structure. 6 Chemistry deals with: 1. What is material made of? 2. What is the makeup and internal arrangement of the atoms? 3. How does it behave when heated, cooled or mixed with other materials? 7 Branches of Chemistry Organic chemistry – the study of carbon containing compounds. Inorganic chemistry – the study of substances that do not contain carbon (metals and gases). Physical chemistry – the study of the properties and changes of matter and their relation to energy. 8 Analytical chemistry –the identification of the components and composition of materials. Biochemistry – the study of the processes occurring in living systems. 9 Types of Research 10 Basic Research - carried out for the sake of increasing knowledge. Most basic research is carried out in universities. Research is normally published in scientific journals. Types of Research 11 Applied Research - carried out to solve a problem. Research is carried out by companies to make a profit. Usually short term goals set by the company. Summary 1) Define the word chemistry. 2) Name the five branches of chemistry. 3) Define basic and applied research. 12 Chapter 3 Matter and its Properties 13 What is Matter? 14 Matter is anything that takes up space (volume) and has mass. Mass is the amount of matter in an object. Usually measured with a balance. Volume is the amount of three dimensional space an object occupies. Building Blocks of Matter 15 The fundamental building blocks of matter are atoms. Atoms – the smallest unit of an element that maintains the properties of the element. Element – a pure substance made of only one kind of atom. Element Examples – carbon, hydrogen and oxygen. The periodic table lists all the elements. Elements contain only one kind of atom. 16 17 Compound – a substance that is made from the atoms of two or more elements that are chemically bonded. Compound Examples – water (made of hydrogen and oxygen), methane (made of carbon and hydrogen) and sugar (made from carbon, hydrogen and oxygen). H2O, CH4 and CxHxOx Properties and Changes in Matter Every substance, whether it is an element or a compound, has characteristic properties. Chemists use properties to distinguish between substances and to separate them. Properties can help reveal the identity of an unknown substance. 18 Properties and Changes in Matter Properties can also be grouped into two general types: physical and chemical. Physical – a property that can be observed or measured without changing the identity of the substance. Such properties include: color, shine, hardness, melting point and boiling point. 19 Properties and Changes in Matter A physical change in a substance does not involve a change in the identity of the substance. Examples include: grinding, cutting, melting and boiling the substance. These changes do not change the identity. 20 Chemical – a property that relates to a substance’s ability to undergo changes that transform it into different substances. Such properties include: burning of wood, rusting of iron (Fe2O3) and tarnishing of silver. When charcoal (carbon) burns, it combines with oxygen in the air to form carbon dioxide. The charcoal and oxygen no longer exists in their original form. 21 Properties and Changes in Matter A chemical change is when a substance is converted into a different substance. The substances that react (starting material) in a chemical change are called the reactants. The substances that are formed by the chemical change are called the products. 22 Properties and Changes in Matter In the example of burning of charcoal, carbon and oxygen are the reactants in the combustion reaction. Carbon dioxide is the product. carbon + oxygen C + O2 (reactants) 23 carbon dioxide CO2 (product) Problem Would the dissolving of sugar in water be a physical or chemical change? 24 Answer Dissolving of sugar into water is a physical change. If you were to evaporate the water from the container you would be left with sugar. It has not changed to a different substance. 25 Indications of a chemical reaction Energy absorbed or released Color change Odor change Precipitate - solid that separates from solution Not easily reversed 26 Classwork Page 94 Questions: 38 and 43 27 States of Matter The three common states of Matter: Solid Liquid Gas 28 Solid State – matter in the solid state has definite volume and shape. The particles that make up the solid are packed close together in relatively fixed positions. The particles are held close together by strong attractive forces. 29 Liquid State – matter in the liquid state has definite volume but an indefinite shape. A liquid assumes the shape of its container. The particles that make up the liquid are packed close together but can move past one another. The rapidly moving particles cause them to temporarily overcome the attractive forces between them, allowing the liquid to flow. 30 Gas State – matter in the gas state has no definite volume nor shape. Gases have this characteristic because they are composed of particles that move very rapidly and are at great distances from one another. At these distances, the attractive forces are very weak. A gas will expand to fill any size container and take the shape of that container. 31 Condense Freeze Evaporate Melt Solid 32 Liquid Gas States of Matter Definite Definite Temp. ComVolume? Shape? increase pressible? Solid Liquid Gas 33 YES YES NO YES Small Expans. NO NO Small Expans. NO NO Large Expans. YES Homework Homework Set 1 Due: 34 Law of Conservation of Mass Mass can not be created or destroyed in ordinary (not nuclear) changes. All the mass can be accounted for. Mass at the start = mass at end 35 Energy and Changes in Matter When physical or chemical changes occur, energy is always involved. The energy can take the form of heat or light. Heat provides enough energy to cause physical changes – melting of ice. 36 Energy and Changes in Matter Heat can also cause a chemical change – the decomposition of water to form oxygen and hydrogen gas. The Law of Conservation of Energy – although energy can be absorbed or released in a chemical reaction, it is not destroyed or created, it simply assumes a different form. 37 Types of Matter All matter can be classified into one of two groups: pure substances or mixtures. Pure Substance – can be an element or compound. The composition of a pure substance is the same throughout and does not vary from sample to sample. Examples include: water, sugar, gold and aluminum. 38 39 Mixture – contains more than one substance. They can vary in composition and properties from sample to sample. Examples include: sugar dissolved into water, granite, brass, chocolate chip cookie and air. Mixtures Homogeneous- same composition throughout. Homogenous mixtures are also called solutions. Example: salt water solution and air Heterogeneous- mixture is not the same throughout the sample. Example: sand and water. The heavier sand settles to the bottom. Example: Italian salad dressing 40 Solutions Homogeneous mixture Can occur between any state of matter. Solid in liquid- Kool-aid Liquid in liquid- antifreeze in a car radiator Gas in gas- air (oxygen, nitrogen and argon) Solid in solid - brass Liquid in gas- water vapor 41 Separating mixtures Only a physical change- no new matter Filtration - separate solids from liquids with a barrier (filter paper) Distillation - separate liquids because of different boiling points – Heat mixture – Catch vapor in cooled area Chromatography - different substances are attracted to paper or gel, so move at different speeds 42 43 Pure Substances In contrast to a mixture, a pure substance is always homogeneous. A pure substance has a fixed composition. 1) Every sample of a given pure substance has exactly the same characteristic physical and chemical properties. 2) Every sample of a pure substance has exactly the same composition. 44 Pure Substances Pure substances are either elements or compounds. A compound can be broken down, or decomposed, into two or more simpler elements by a chemical change. Water is made from hydrogen and oxygen atoms bonded together. H2O 45 Pure Substances Water can be broken down into the hydrogen and oxygen atoms through a chemical reaction called electrolysis. This involves passing an electric current through water. When broken down, water contains 11.2% hydrogen and 88.8% oxygen 46 Pure Substances Sucrose (sugar) is made of carbon, hydrogen and oxygen. Sucrose breaks down into carbon and water when heated to high temperatures. 47 Summary 48 Classwork Pages 95: Questions 62, 63 and 64 49 Homework Homework Set 2 Due: 50 Chapter 1 Section 3 Elements and the Periodic Table 51 Element – a pure substance made of only one kind of atom. Element – pure substance that cannot be decomposed by chemical changes. Elements serve as the building block of matter. Each element has characteristic properties. 52 Periodic Table Elements – are organized into groups based on similar chemical properties. Periodic Table – The organization of elements is the periodic table. Each box on the periodic table lists one element and the letter symbol. 53 Chemical Symbols There are 111 elements Each has a 1 or two letter symbol First letter always capitalized second never Don’t need to memorize Some from Latin or other languages 54 Chemical Symbols Used to write chemical formulas Subscripts tell us how many of each atom H 2O C 3H 8 H2CO3 55 Periodic Table Groups or Families – the vertical columns of the periodic table. The groups are number 1 to 18 from left to right. Each group contains elements with similar chemical properties. 56 Periodic Table Alkaline Earth Metals – Group 2 of the periodic table. Elements include beryllium, magnesium, calcium, strontium, barium and radium. All of these elements are reactive metals with similar bonding abilities. 57 Periodic Table Periods – the horizontal rows of elements in the periodic table. Physical and chemical properties change across a period. Elements on opposite sides of the periodic table in the same row are much different. Example is lithium and fluorine in Period 2. 58 Types of Elements 59 The periodic table is broadly divided into two main sections: metals and nonmetals. The metals are at the left and the center of the table. The nonmetals are toward the right. 60 Metals 61 Metal – an element that is a good conductor of heat and electricity. Properties: solids (mercury), shines, malleable (hammered), ductile (drawn into thin wires), resistance to breaking, conductors of heat and electricity. Nonmetals Nonmetal – an element that is a poor conductor of heat and electricity. Properties: Gases – nitrogen, oxygen, fluorine and chlorine. Liquids – bromine Solids – carbon, phosphorus, sulfur, iodine 62 Nonmetals Properties: The solids tend to be brittle rather than malleable or ductile. Low conductors of heat and electricity. 63 Metalloids 64 Metalloids – an element that has some characteristics of metals and nonmetals. A stair-step line separates the metals from the nonmetals on the periodic table. Metalloids Properties: All metalloids are solids at room temperature. Less malleable than metals but not as brittle as nonmetals. Metalloids tend to be semiconductors of electricity. (intermediate between metals and nonmetals). 65 Metalloids Properties: Metalloids are used in semiconducting materials found in computers, calculators, televisions and radios. 66 Elements include: boron, silicon, germanium, antimony Metal or Nonmetal 67 1) Ti 6) C 2) Li 7) Ca 3) Pd 8) Zr 4) I 9) Ni 5) N 10) S Noble Gases Noble Gases - the elements in Group 18 of the periodic table. They are considered nonmetals. These elements are generally unreactive. All are gases at room temperature. Examples: neon, argon, krypton, xenon (all used in lighting) and helium. 68 Classwork Pages 95/96: Questions 67, 70 and 82 69 Homework Homework Set 3 Due: 70 End of Chapter 1 71 Energy The ability to do work. Work - cause a change or move an object. Many types- all can be changed into the other. 72 Types of Energy Potential- stored energy Kinetic Energy- energy something has because its moving Heat- the energy that moves because of a temperature difference. Chemical energy- energy released or absorbed in a chemical change. Electrical energy - energy of moving charges 73 Types of Energy Radiant Energy- energy that can travel through empty space (light, UV, infrared, radio) Nuclear Energy – Energy from changing the nucleus of atoms All types of energy can be converted into others. If you trace the source far enough back, you will end up at nuclear energy. 74 Conservation of Energy Energy can be neither created or destroyed in ordinary changes (not nuclear), it can only change form. Its not just a good idea, its the law. 75 What about nuclear? E = mc2 2 energy = mass x (speed of light) 8 speed of light = 3 x 10 A little mass can make a lot of energy Law of Conservation of Mass - Energy the total of the mass and energy remains the same in any change 76