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Chapter 2 The Chemistry of Life 1 Section 1 The Nature of Matter 2 Atoms Atoms: Basic unit of matter. Greek word atomos. “unable to be cut” Factoid: Atoms are so small that if you lined up 100 million of them, they would barely be the width of your pinky. 3 Though atoms are small, they are made of even smaller particles. P. 35, fig. 2-1 Protons-+ charged Neutrons-no charge Electrons- (-) charged 4 Protons & neutrons are bound together in the nucleus of an atom. Electrons are in constant motion around the nucleus of an atom. Atoms have equal numbers of protons & electrons. 5 Electrons travel around the nucleus in an electron cloud. They travel in what are called orbitals. Each orbital contains a certain # of electrons. 1st orbital has 2e 2nd orbital has 8e 3rd orbital has 8e 4th orbital has 8e 6 7 What Element is This? 8 Elements & Isotopes Elements –substances that consist of entirely of 1 type of atom. Over 100 elements exist, but only about 25 are vital to living things. The 4 most important elements are: Hydrogen Carbon Nitrogen Oxygen Elements are abbreviated by symbols. H C N O 9 Atomic number: # above the symbol of the element. This number represents the # of electrons & protons in that element. Example: Look at Carbon (C) What is it atomic #? 6 What does this mean? 6e & 6p 10 Isotopes Isotopes: Atom of an element that have a different # of neutrons then that of other atoms of the same element. The sum of protons & neutrons in an atom is called the atomic mass or atomic weight. Some examples: Carbon-12 Carbon-13 Carbon-14 P. 36, fig. 2-2 11 Isotopes are identified by their mass #. Since isotopes have the same # of electrons, they have the same chemical properties. 12 13 Radioactive Isotopes Some isotopes are radioactive. This means that their nuclei are unstable & they breakdown over time. This radiation can be dangerous. But, scientists have a number of uses for them: Can be used to treat cancers. Can be used to age rocks & other items. Can be used as a tracer in human organs. 14 Chemical Compounds In nature most elements are found in compounds. Compounds –a substance formed by 2 or more elements. These compounds are usually written as formulas such as: NaCl H20 CO2 15 Chemical Bonds Compounds are held together by chemical bonds. Bond formation involves the electrons that surround an atom. AKA Valence Electrons The main types of chemical bonds are: Ionic Covalent 16 Ionic Bonds Ionic bond –when one or more electrons are transferred from one atom to another. Atoms that lose an electron have a pos. charge. Atoms that gain an electron have a neg. charge. Na+ Cl- Pos. & neg. charged atoms are called ions. Pos. atoms are cations. Neg. atoms are anions. 17 P. 38, fig. 2-3 shows a ionic bond b/t Na & Cl. Na will easily lose an electron b/c it is a + Na ion. Likewise, Cl will easily gain an electron b/c it is a Cl ion. 18 Ionic Bond http://www.youtube.com/watch?v=xTx_DWbo EVs&feature=player_detailpage http://www.youtube.com/watch?v=G49gxlIlSIc 19 Covalent Bonds Covalent Bonds –a bond formed when electrons are shared b/t atoms. You can have single, double, or triple covalent bonds. Molecules are formed when atoms are joined via a covalent bond. Read bottom paragraph on p. 38 A molecule is the smallest unit of most compounds. P. 38, fig. 2-4 20 Covalent Bonding http://www.youtube.com/watch?v=lGEA5PVW QiQ&feature=related 21 Van der Waals Forces Van der Waals Forces –a slight attraction that develops b/t the opposite charged regions of nearby molecules. Example: A gecko’s toes. Fig. 2-5 22 Chapter 2 Section 2 Properties of Water 23 75% of the Earth is covered by water. 24 The Water Molecule Water = H2O Water exists in 3 states: Liquid Gas Solid Water as a molecule has a neutral charge. Figure it out…. 10e- & 10p+ 25 Characteristics of Water Polarity: Water molecules are polar b/c there is an uneven distribution of e- b/t the O & H atoms. 26 Hydrogen Bonds: B/c water is polar, it can attract other water molecules. Fig. 2-7 The (+) & (-) charges are weaker than the charges of + & - ions. 27 28 When 2 or more water molecules join up, they are held there by a hydrogen bond. Hydrogen Bond 29 Hydrogen bonds are weaker than ionic or covalent bonds. Also, a water molecule can bond to 4 other water molecules at a time. This enables water to have some interesting properties. 30 http://www.youtube.com/watch?v=KiZJOTt3D l0&feature=related 31 Cohesion –attraction b/t molecules of the same substance. Example: Water forms beads on a smooth surface. The reason why some insects can walk on water. AKA surface tension or water tension. Fig. 2-8 32 Adhesion –an attraction b/t molecules of different substances. Example: Capillary action 33 34 35 Solution & Suspensions Water isn’t always pure, it is often found in a mixture. Mixture –a material composed of 2 or more elements or compounds that are physically mixed together, but not chemically combined. Examples: Salt & pepper Sand & sugar Earth's atmosphere & its gases 36 The 2 types of mixtures that can be made w/ water are: Solutions Suspensions 37 Solutions Solution –a homogeneous mixture of 2 or more substances in which the molecules are evenly distributed. Solute –substance which is dissolved. Solvent –substance that dissolves the solute. Examples: Salt water Sugar water Fig. 2-9 Water is the greatest solvent on Earth! 38 Suspensions Suspension – mixture of water & nondissolved substances. blood Oil & Water Sand & water 39 Acids, Bases, & pH The pH Scale Fig. 2-10 Pure water = 7 40 Acids Acid –any compound that forms H+ ions in a solution. Ex: Hydrochloric acid Sulfuric acid Nitric acid 41 Bases Base –a compound that produces OH- ions in a solution. Examples: Lye Ammonia Oven cleaner 42 Buffers The pH of fluids w/in cells in the human body are generally between 6.5-7.5. If higher or lower it may interfere w/ chem. reactions. Buffers have a lot to do w/ maintaining ph in our bodies & therefore our homeostasis. Buffers –weak acids or bases that can react w/ strong acids or bases to prevent sudden changes in pH. 43 Section 2-3 Carbon Compounds 44 Read the 1st paragraph…. 45 The Chemistry of Carbon Carbon is heavily studied in chemistry for a few reasons: C atoms have 4 valence e-. This means that C can join w/ many other atoms via strong covalent bonds. C can bond such elements as: H, O, P, S, & N 46 Also, C can bond to other C atoms. This gives C the ability to form chains. These chains can be unlimited in length. 47 Carbon-carbon bonds can be: Single 2e Double 4e Triple 6e 48 Carbon can form: Chains Rings Branches 49 Macromolecules Macromolecules –extremely large molecules found in living orgs. “Giant molecules” Macromolecules are made of thousands or even hundreds of thousands of molecules. 50 Macromolecules are made by polymerization. In this process, large compounds are formed by joining smaller ones together. The smaller units, called monomers join to form polymers. Monomers can be identical or they can be like beads multicolored necklace. 51 There are 4 groups of organic carbon compounds found in living things: Carbohydrates (Carbs) Lipids Proteins Nucleic acids 52 Carbohydrates Carbohydrates –compounds made up of C, H, & O atoms. Usually in the ratio of 1:2:1 Ex: C6H12O6 Orgs. use carbohydrates as a main source of energy (E). 53 Examples of Carbs: Starch Sugars Cellulose We break down sugars for energy. Plants store energy in starches. 54 Single sugar molecules = monosaccharides Ex: Galactose Fructose Glucose NOTE: Items them end in “ose” are sugars. 55 2 sugar molecules = disaccharides Ex: Glucose + Fructose = Sucrose A large macromolecule formed from many monosaccharides is a polysaccharide. Ex: Glycogen Also known as animal starch. Plants have cellulose & starch as their polysaccharides. 56 Lipids Lipids –a carbon compound made from mostly C & H. Usually insoluble in water. Examples: Fats Oils Waxes Steroids 57 Lipids are used for: Storing energy Parts of cell membranes Waterproof coatings Fig. 2-14 Glycerol & a fatty acid 58 3 types of fatty acids: Saturated fatty acid Unsaturated fatty acid Has the maximum # hydrogen atoms. Has at least 1 double carbon-carbon bond. Polyunsaturated fatty acid Contain more than 1 carbon-carbon double bond. 59 60 Nucleic Acids Nucleic acids –macromolecules containing H, O, N, C, & P. Nucleic acids are polymers made up of nucleotides. Nucleotides –consist of 3 parts: A sugar A phosphate group A nitrogen base Fig. 2-15 61 Nucleic acids store transmit genetic info. There are 2 types: DNA RNA 62 Proteins Macromolecules that contain N as well as C, H, & O. Proteins are polymers of molecules called amino acids. Amino acids are the building blocks of proteins. So, AA’s are monomers of proteins. 63 Proteins are some of the most diverse macromolecules. There are more than 20 AA in nature. AA are held together by peptide bonds. Peptide bonds are covalent bonds. The instructions for how AA are put together is stored in our DNA. 64 Proteins do quite a few things for us. They: Control the rate of reactions Regulate cell processes Used to form bones & muscle Used for transport of substances Immune responses 65 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 Carbon, hydrogen, oxygen which contain which contain Carbon,hydrogen, oxygen, nitrogen, phosphorus Carbon, hydrogen,oxygen, nitrogen, 66 Section 2-4 Chemical Reactions & Enzymes 67 Chemical Reactions Chemical Reaction – process that changes, or transforms, one set of chemicals into another. Chemical reactions can happen very slowly or very quickly. Ex: Rust formation on iron. (slow) P. 49, fig. 2-18 Chemical reactions always involve the breaking of chemical bonds. 68 69 Look at this Reaction: P. 49 Carbon Dioxide Water Carbonic Acid CO2 + H2O H2CO3 Reactants Products 70 Energy in Reactions Chemical reactions can release E. Called an exothermic reactions. This release can be in the form of: Heat Light Sound Chemical reactions can also absorb E. Called an endothermic reactions. 71 Every org. must have a source of E to carry out chemical reactions. Where do they get this E? Plants get E through photosynthesis. Animals get their E by consuming plants or animals If you want to breathe, grow, think, or dream you need a chemical reaction. Chemical reactions occur when you metabolize, or break down, digested food. 72 Activation Energy Activation energy –E that is needed to get a reaction started. P. 50, fig. 2-19 73 Energy Absorbing Activation Energy 74 Energy Releasing Activation Energy 75 76 Enzymes Some chemical reactions are too slow or have too high of a activation E to make them practical. To make these reactions a possibility you need a catalyst. Catalyst –substance that speeds up a chemical reaction. Catalysts lower the activation E required by a reaction. 77 Enzymes –proteins that act as a biological catalyst. Enzymes speed up chemical reactions that take place in cells. P. 51, fig. 2-20 Enzymes are very specific. They usually only catalyze one chemical reaction. Enzymes are often named after the reaction they catalyze. 78 Enzyme Action How enzymes do their job: P. 52-53 You have 3 parts: The Enzyme The Substrates The Enzyme-Substrate Complex P. 53, fig. 2-22 bottom Substrates –the reactants of enzyme-catalyzed reactions. 79 Enzyme Substrate Complex 80 Regulation of Enzyme Activity Enzyme activity can be affected by: Temp Most enzymes work well at 37ºC. pH Cells can also control enzyme activity. They have proteins that act as keys to enzyme activity. On/off 81 Enzymes are essential for: Regulating chemical pathways. Making materials that cells need. Releasing energy Transferring information 82 83