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The Chemistry of Life Chapter 2 Atoms “Unable to be cut” Element-pure substance composed of only one type of atom Isotope-atoms of same element containing different numbers of neutrons Nucleus Protons- + Mass = 1 The sum of Protons and Neutrons is the mass number Neutrons- 0 (neutral) Mass = 1 Electron Charge = -1 Mass = 1/1840 Attracted to positively charged nucleus but their constant motion prevents them from entering the nucleus Because atoms have equal numbers of electrons and protons atoms are neutral. Isotopes Atoms of an element that have differing numbers of neutrons Because they have the same number of electrons, all isotopes of an element have the same chemical properties Simple elements Compound Chemical compounds Chemical Compounds A substance formed by the chemical combination of two or more elements Hydrogen gas + Hydrogen gas + Oxygen gas = H2O Chemical Compounds Physical and chemical properties of a compound can be very different from the elements that make it Sodium-a silver-colored metal that can be cut with a knife Chlorine-a poisonous, greenish gas that was used to kill soldiers in WWI Chemical Bonds-The Glue Ionic Bondstransferring electrons from one atom to another Covalent Bonding Covalent Bonds form when electrons are shared between atoms. Van der Waals Forces Minor attractions between molecules Involves opposite charges Water O + + + + + H+ ++ + + - - Hydrogen Bonds Cohesion-an attraction between molecules of the same substance Allows water to form droplets on smooth surfaces Hydrogen Bonds Water molecules attract each other because of partial charges Polar molecule charges are written in ( ) The ability of water to form multiple bonds gives it important characteristics A single water molecule may form up to four H-bonds Water Cohesion-attraction to itself Adhesion-attraction to other substances Capillary action-moves water against gravity in tiny tubes Surface Tension Cohesion Mixing it Up Mixture- two or more elements or compounds that are physically mixed together but not chemically joined. Ex. Sugar and sand mixed together Suspension-mixtures of water and undissolved particles Solution: all components are evenly distributed Ex. Salt water Solute Solvent pH H2O Water H+ + OH- Hydrogen Ion + Hydroxide Ion Acids Acid- any compound that forms H+ in solution Have higher concentrations of Hydrogen ions than pure water 7 Have pH values BELOW 7 ACIDS Bases Compounds that produce OH(hydroxide) ions in solution. Basic solutions contain lower concentrations of H+ ions than pure water and have a pH value greater than 7. Bases 7 Common Solutions Acidic Tomato Juice Lemon Juice Soda Basic Ammonia Bleach Soap Buffer pH of Human body is between 6.5 and 7.5 Buffers- weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH Carbon Compounds Organic-contains carbon Four groups of organic compounds making up living things are Carbohydrates Lipids Nucleic Acids Proteins Carbohydratesstarches and sugars Lipids-fats, oils and waxes Nucleic Acids-DNA and RNA Proteins- linked amino acids Carbohydrates Compounds of C, H, and O Living things use carbohydrates as their main source of energy Plants and some animals can use carbohydrates for structure Living things store extra sugar as complex carbohydrates known as starch “carbon hydrate” Cx(H2O)x Formed when a carbon compound (CO2) reacts with water Uses Energy Structure Cell Recognition Protection Monosaccharide Monomer Simplest sugar Glucose Galactose Fructose Ribose MonoSaccharThey consist of one sugar and are usually colorless, water soluble, crystalline solids Glucose Fructose Disaccharide Covalent bond links two monosaccharides results in disaccharide Lactose-milk Sucrose-plants Maltose-grains DiSaccharSucrose= glucose + fructose Lactose= glucose + galactose Maltose = glucose + glucose Lactose Sucrose Sucrose Sucrose Sucrose Starches Glycogen Cellulose Chitin Starch Starch Potato Corn Oats Cellulose Cellulose Chitin Carbohydrates Lipids Fats, oils, and waxes Generally not soluble in water Many are made of a glycerol molecule with compounds of fatty acids attached. Saturated-has all possible H atoms attached Un-saturated- has at least one double bond occupying an atom’s position Glycerol Backbone Saturated Unsaturated Saturated Fats Saturated Fats Unsaturated Fats Tend to be liquid at room temperature Come from vegetable sources Has at least one carbon-carbon bond Polyunsaturated-has more than one double bond Corn oil, sesame oil, canola oil, and peanut oil are polyunsaturated Unsaturated Fats Peanut Oil Corn Oil Canola Oil Nucleotides Nucleic acids are assembled from individual monomers known as nucleotides Nucleotides have a 5-carbon sugar, a phosphate group, and a nitrogenous base. Nucleotide Nucleic Acids Store and transmit hereditary or genetic information. Ribonucleic acid (RNA)- contains the sugar ribose Deoxyribonucleic acid (DNA)- contains the sugar deoxyribose Arranged in sequence to form informational code that Deoxyribonucleic Acid Deoxyribose-monosaccharide Ribonucleic Acid Ribose- monosaccharide Ribonucleic Acid Proteins Macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen Polymers, they are made of monomers called amino acids. There are more than 20 amino acids found in nature. Some amino acids are acidic or basic. Some are polar. Some are non-polar. Proteins The instructions for arranging amino acids into many different proteins are stored in DNA. Some proteins control the rate of reactions, some form muscles, and some transport substances or fight disease. Proteins Protein Transport Enzymes Enzymes Speed up chemical reactions that take place in cells Functioning depends on shape of twisted protein Temperature and pH change shape of proteins and so change functioning of enzymes Chemical Reactions Process that changes one set of chemicals into another set of chemicals Reactants- go into the reaction Products- come out of the reaction Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products Baking Soda + Vinegar CH3COOH + NaHCO3 H2CO3 Carbonic Acid Salt and Carbonic Acid CH3COONa + H2CO3 H2O + CO2 Water and Carbon Dioxide Energy in Reactions Reactions that release energy often occur spontaneously Reactions that absorb energy will not occur without a source of energy. 2H2 + O2 2H2O Burning releases energy But . . .what do you have to have to start the fire? Releasing Energy Activation Energy The energy that is needed to get a reaction started Activation Energy Energy-Absorbing EndoTherm- Endo/Exo The reaction that changes water into hydrogen and oxygen gas absorbs so much energy that it generally can’t occur by itself. Water can be made through the burning reaction of Hydrogen and Oxygen which produces lots of energy and water. Energy Releasing ExoTherm- Catalyst Some chemical reactions that make life possible are too slow or have activation energies that are too high to make them practical for living tissue. Amylase on cracker Catalyst Enzymes Proteins that act as biological catalysts Speed up chemical reactions that take place in cells Carbonic anhydrase speeds up CO2 removal by a factor of 10 million