Q. What is Chemistry? A. The science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions. Go to Section: Interest Grabber Section 2-1 What’s the Matter? All of the materials around you are made up of matter. You are made up of matter, as are the chair you sit on and the air you breathe. 1. Give an example of solid matter. 2. Give an example of liquid matter. 3. Give an example of gaseous matter. 4. Is all matter visible? 5. Does all matter take up space? Go to Section: AHSGE Alert!!! How does the motion of molecules differ in each of the three states of matter? Solids? Liquids? Gases? Go to Section: 2-1 The Nature of Matter Elements – substances that cannot be broken down into simpler chemical substances. (90 elements occur naturally.) Atom –the basic building block of all matter; the smallest particle of an element that has the characteristics of that element. Subatomic Particles- parts of the atom ►Protons- positive charged particles found in the nucleus (center of the atom) ► Neutrons- Neutral particles found in the nucleus of the atom ► Electrons- Negative charged particles found in the outer energy levels of the atom. 1st – 2, 2nd – 8, 3rd – 18, 4th – 32 Go to Section: Go to Section: 2-1 The Nature of Matter Terms to Know Isotopes – atoms of the same element with the same number of protons but a different number of neutrons. Compound – a substance that is composed of two or more elements chemically combined. Covalent bond – formed when atoms share electrons. Examples are sugars, fats, proteins, and water. Molecule – a group of atoms held together by a covalent bond. Ionic bond – formed when atoms gain or lose electrons. Ion – a charged particle Go to Section: Figure 2-2 Isotopes of Carbon Section 2-1 Nonradioactive carbon-12 Nonradioactive carbon-13 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons Go to Section: Radioactive carbon-14 6 electrons 6 protons 8 neutrons Figure 2-3 Ionic Bonding Section 2-1 Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Go to Section: Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1 An Element in the Periodic Table Section 2-1 6 Element Symbol Element Name Go to Section: Atomic # C Carbon 12.011 Atomic Mass (Mass #) Determining the Number of Subatomic Particles Atomic number – the total number of protons in the nucleus of an atom. Mass number – the total number of protons and neutrons in the nucleus of an atom. To determine the number of protons: look at the atomic number To determine the number of electrons: look at the atomic number To determine the number of neutrons: round the atomic mass and subtract the atomic number Families- columns Periods- rows Go to Section: An Element in the Periodic Table Section 2-1 6 Element Symbol Element Name Go to Section: Atomic # C Carbon 12.011 Atomic Mass (Mass #) An Element in the Periodic Table Section 2-1 5 Element Symbol Element Name Go to Section: Atomic # B Boron 10.81 Atomic Mass (Mass #) Examples for Determining Subatomic Particles Fe (Iron) - 26 protons, 26 electrons, (59 – 26) 33 neutrons B (Boron) – 5 protons, 5 electrons (11 – 5) 6 neutrons P (Phosphorus)– 15 protons, 15 electrons, (31 – 15) 16 neutrons Na (Sodium)-11 protons, 11 electrons, (23 – 11) 12 neutrons Go to Section: 2-2 Properties of Water Water – the most important compound in living organisms; Water makes up 70 to 95 percent of most organisms. Polarity Water is a polar molecule. A polar molecule has an unequal distribution of charge. Water can dissolve many ionic compounds such as salt as well as many polar molecules such as sugar. Hydrogen Bonds – the force of attraction that occurs with a hydrogen atom Cohesion – the attraction between molecules of the same substance Adhesion – the attraction between molecules of different substances Go to Section: 2-2 Mixtures and Solutions Mixture – a combination of substances in which the individual components retain their own properties. Solution – a mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent). Example: Salt Water Suspension – a mixture in which one of the substances does not completely dissolve and will settle to the bottom Example: blood Go to Section: Figure 2-9 NaCI Solution Section 2-2 ClCl- Na+ Na+ Water Go to Section: Water ACIDS, BASES AND pH Acid – any substance that forms hydrogen (H+) ions in solution. Base – any substance that forms hydroxide ions (OH-) in solution. pH scale – a measure of how acidic or basic a solution is. Below 7 is acidic; above 7 is basic; 7 is neutral. The pH of most cells must be kept between 6.5 and 7.5. In order for the body to maintain a consistent pH, our body contains buffers. Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH. Go to Section: pH Scale Section 2-2 Increasingly Basic Oven cleaner Increasingly Acidic Neutral Go to Section: Bleach Ammonia solution Soap Sea water Human blood Pure water Milk Normal rainfall Acid rain Tomato juice Lemon juice Stomach acid Interest Grabber Section 2-3 Life’s Backbone Most of the compounds that make up living things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms. As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain. Go to Section: Concept Map Section 2-3 Carbon Compounds include Carbohydrates Lipids Nucleic acids Proteins that consist of that consist of that consist of that consist of Sugars and starches Fats and oils Nucleotides Amino Acids which contain which contain Carbon, hydrogen, oxygen Go to Section: Carbon, hydrogen, oxygen which contain which contain Carbon,hydrogen, oxygen, nitrogen, phosphorus Carbon, hydrogen,oxygen, nitrogen, 2-3 CARBON COMPOUNDS Monomers – small units Polymers – larger units formed from monomers Organic Compounds – contain the element carbon I. Carbohydrates 1. sugars and starches 2. C, H, O 3. simplest is monosaccharide (single sugar) 4. Monsaccharides can join together and form polysaccharides. Polysaccharides are the form in which living things store excess sugar. plants - starch animals - glycogen Go to Section: ORGANIC COMPOUNDS II. Lipids 1. Organic compounds that are waxy and oily. 2. Used to store energy, form biological membranes. 3. Fats, oils, and waxes. 4. Plants and animals use lipids for storing energy. They provide more energy than carbohydrates. Sterols are types of lipids. A common type of sterol is cholesterol. Go to Section: ORGANIC COMPOUNDS III. Proteins 1. contain N, C, H and O 2. polymers of amino acids 3. more than 20 different amino acids 4. help to carry out chemical reactions 5. one type of protein is an enzyme (it is a catalyst that speeds up a reaction). Enzymes lower the amount of energy needed to start a reaction. 6. Important in regulating chemical pathways, synthesizing materials needed by cells, releasing energy, and transferring information. Go to Section: Figure 2-17 A Protein Section 2-3 Amino acids Go to Section: ORGANIC COMPOUNDS IV. Nucleic Acids 1. contains C, O, H, N, and P 2. polymers of individual monomers known as nucleotides 3. Two basic kinds RNA (ribonucleic acid) and DNA (deoxyribonucleic) Go to Section: Interest Grabber Section 2-4 2-4 Matter and Energy Have you ever sat around a campfire or watched flames flicker in a fireplace? The burning of wood is a chemical reaction—a process that changes one set of chemicals into another set of chemicals. A chemical reaction always involves changes in chemical bonds that join atoms in compounds. The elements or compounds that enter into a chemical reaction are called reactants. The elements or compounds produced by a chemical reaction are called products. As wood burns, molecules of cellulose are broken down and combine with oxygen to form carbon dioxide and water vapor, and energy is released. ►On your own sheet of paper write down the reactants and products in this reaction. Go to Section: 2-4 CHEMICAL REACTIONS AND ENZYMES Chemical Reactions – when two or more substances combine together producing new substances with different properties. Reactants Products Metabolism – all of the chemical reactions that occur within an organism. Activation Energy – the energy that is needed to start a reaction Catalyst – a substance that speeds up a chemical reaction by lowering the amount of energy needed to start the reaction. Enzymes – special biological catalyst (type of protein) Go to Section: Effect of Enzymes Section 2-4 Reaction pathway without enzyme Activation energy without enzyme Reactants Reaction pathway with enzyme Activation energy with enzyme Products Go to Section: Videos Click a hyperlink to choose a video. Atomic Structure Energy Levels and Ionic Bonding Covalent Bonding Enzymatic Reactions Video 1 Atomic Structure Click the image to play the video segment. Video 2 Energy Levels and Ionic Bonding Click the image to play the video segment. Video 3 Covalent Bonding Click the image to play the video segment. Video 4 Enzymatic Reactions Click the image to play the video segment. Go Online Career links on forensic scientists Interactive test Articles on organic chemistry For links on properties of water, go to www.SciLinks.org and enter the Web Code as follows: cbn-1022. For links on enzymes, go to www.SciLinks.org and enter the Web Code as follows: cbn-1024. Interest Grabber Answers 1. Give an example of solid matter. Sample answers: books, desks, chairs 2. Give an example of liquid matter. Sample answers: water, milk 3. Give an example of gaseous matter. Sample answers: air, helium in a balloon 4. Is all matter visible? No 5. Does all matter take up space? Yes Interest Grabber Answers 1. Working with a partner, make a list of ten things that have water in them. Possible answers: bodies of water, rain and snow, soft drinks and other beverages, juicy foods such as fruits, and so on. 2. Exchange your list for the list of another pair of students. Did your lists contain some of the same things? Did anything on the other list surprise you? Students’ answers will likely be similar, but not exactly alike. 3. Did either list contain any living things? Students’ lists may include plants, animals, or other living things. Interest Grabber Answers 1. On a sheet of paper, make a list of at least ten things that contain carbon. Students will likely know that charcoal and coal contain carbon. They may also list carbohydrates (starches and sugars), oil, gasoline, wood, or carbon dioxide. 2. Working with a partner, review your list. If you think some things on your list contain only carbon, write “only carbon” next to them. Students will say that charcoal and coal contain only carbon. While these materials do contain small amounts of other elements, such as sulfur, they are composed mostly of carbon. 3. If you know other elements that are in any items on your list, write those elements next to them. Students may know that many carbon compounds also contain oxygen and/or hydrogen. Interest Grabber Answers 1. What are the reactants when wood burns? Reactants are oxygen and cellulose. 2. What are the products when wood burns? Products are carbon dioxide and water. 3. What kinds of energy are given off when wood burns? Light and heat are given off. Some students may also mention sound (the crackling of a fire). 4. Wood doesn’t burn all by itself. What must you do to start a fire? What does this mean in terms of energy? To start a fire, you must light it with a match and kindling. You are giving the wood some energy in the form of heat. 5. Once the fire gets started, it keeps burning. Why don’t you need to keep restarting the fire? Once the fire gets going, it gives off enough heat to start more of the wood burning. This slide is intentionally blank.