The Chemistry of Life Atoms and Their Interactions Water and Diffusion Life Substances

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  • The Chemistry of Life Atoms and Their Interactions Water and Diffusion Life Substances
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  • Atoms Smallest particle of an element that has the characteristics of an element. Basic unit of matter Atomos = (greek) unable to be cut
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  • Atomic Structure and Subatomic Particles Nucleusstrong forces bind protons and neutrons at center of the atom; Protons - + charged particles Neutrons - particles with no charge Electrons - charged particle; 1/1840 mass of proton; constantly in motion in space surrounding nucleus; attracted to protons in nucleus
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  • Electron Energy Levels Electrons travel around the nucleus in certain regions known as Energy Levels. The innermost level (small) maximum of 2 electrons. 2nd level (larger)-up to 8 3rd level-up to18 electrons.
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  • Element Pure substance that consists entirely of one type of atom. Earth Between 88 94 elements occur naturally About two dozen found living organisms)
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  • Trace Elements Elements in living things in very small amounts. (help maintaining healthy cells) Examples: iron and magnesium
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  • What is the most abundant element that exist in living things? (Number)
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  • Most abundant weight
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  • Periodic Table of Elements Periodic-Elements in same group have similar chemical and physical properties Elements and symbols are organized Rows-period; Same number of electron shells Vertical-groups; Electrons in outer energy level
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  • Element
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  • Neutral Atoms # of Electrons = # of protons therefore have no net charge. Same # Electrons = same chemical properties Mass number= Protons + Neutrons
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  • Isotopes Example: Carbon-14 (6 +, 6 -) is an isotope of carbon, 8 neutrons instead of 6 neutrons Carbon 13- 7 neutrons, 6 protons Isotopes-number of electrons same chemical properties Atoms of the same elements that have different numbers of neutrons. Atomic Mass= Average of the masses of an elements isotopes.
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  • RADIO ISOTOPES Isotopes that have unstable nuclei and break down at a constant rate over time. (radiation) Medical Smoke detectors Archeological dating
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  • Radioisotopes in Medicine Detect and treat cance Kill bacteria that causes food to spoil Tracers to follow movement of substances within an organism.
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  • Compounds Substance formed when atoms of two or more elements are chemically combined in definite proportions. Example: H 2 O (2:1), NaCl (1:1)
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  • Compound Unique Characteristics Specific combination of elements in a fixed ratio. Chemically and physically different than elements its comprised. (eg. Water different than H and O) Cannot be broken down into simpler compounds or elements by physical means
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  • Chemical Bonds Force that holds substances together Stability Forming and breaking bonds-provides energy for growth, development, adaptation, and reproduction
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  • Ionic Bonds Electrical attraction b/w 2 oppositely charged atoms or group of atoms.
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  • Ion An atom (or group of atoms) gains or loses electrons has an electrical charge. An ION is a charged particle.
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  • VAN DER WAALS FORCES -EX. HYDROGEN BONDS Molecules close together, slight attraction can form b/w oppositely charged portion of nearby molecules- the intermolecular forces --Helps form water droplets, geckos climb using structures on toes and atoms on surface climbing.
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  • Covalent Bonds A chemical bond formed when two atoms combine by sharing electrons.
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  • Molecule Substances with covalent bonds and having no overall charge. Most compounds in living things. Example : Water, DNA
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  • Covalent Bonds Single-Each atom shares one electron Double- Each atom shares two electrons Triple- Each atom shares three electrons
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  • Chemical Reactions process that changes, or transforms, one set of chemicals into another Chemical bonds formed and broken
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  • Metabolism All chemical reactions that occur within an organism Responsible for break down and building of molecules
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  • How do I know chemical reaction has occurred? Color change - new substances might reflect different colors of light. Heat change - the container may get hotter or colder. Gas produced - bubbles or smoke may be observed. Precipitate formed - an insoluble solid might form in a liquid.
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  • Reactants Substances that undergo chemical reactions.
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  • PRODUCTS a substance obtained from another substance through chemical change
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  • Energy in reactions Energy changes- Some reactions release energy (spontaneous, form of heat), others absorb energy (will not happen w/o energy) Energy Sources-sun >plants>animals Activation Energy- Energy needed to get reaction started.
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  • Mixture A material composed of 2 or more elements or compounds that are physically mixed but not chemically combined
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  • SolutionA mixture in which all the components are equally distributed (salt water solution) SoluteSubstance being dissolved. (salt) SolventSubstance that does the dissolving. (water) Universal solvent is water!!
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  • Suspension Mixture containing non dissolved particles distributed within a solid, liquid or gas. Examples: Orange Juice, Blood, Salad Dressing.
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  • Colloid A thick substance formed when very fine particles (such as large molecules) that cannot be dissolved stay scattered throughout liquid, solid, or gas without sinking. Examples: Gelatin, Toothpaste, Shaving Cream, Smoke and Milk
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  • Tyndall Effect Scattering of light by colloidally dispersed particles. Detected with the aid of a light beam.
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  • Water Liquid most of Earths surface Expands slightly as it changes from liquid to solid Covers 75% of Earths surface Most abundant compound in nearly all living organisms Water resist temperature change
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  • Water continued. Polar MoleculeDue to an uneven distribution of electrons, water molecules are slightly charged on each end. Oxygen has a slight negative charge Hydrogen have a slight positive charge. Strong attraction between water and other molecules; the universal solvent. Dissolve ionic compounds, as well as sugars.
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  • Hydrogen Bonds Weak chemical bond formed by the attraction of the hydrogen atoms to other negatively charged atoms. weak "hydrogen" bonds in water partially get their identity from stronger "covalent" bonds in the H2O molecule
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  • Cohesion Attraction between molecules of the same substance Water forms beads on smooth surface reason insects can walk on water
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  • Surface Tension How difficult it is to stretch or break the surface of a liquid. Water has a high surface tension b/c of cohesion of hydrogen bonds.
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  • Adhesion Attraction b/w molecules of different substances. Eg. Water molecule in a graduated cylinder
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  • Capillary Action Unique property of being able to creep up thin tubes. Water tension and capillary action allow water to move from soil to top of trees.
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  • Heat Capacity Result of hydrogen bonds b/w water molecules is that it takes large amount of heat energy to cause molecules to move faster Large bodies of water absorb large amounts of heat w/ small changes in temperature Organisms in water are protected from drastic change Cell level-water absorbs heat produced by cell processes, regulating cell temperatures
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  • pH-Acids and Bases pH ScaleA measurement system that indicates the relative concentrations of hydrogen and hydroxide ions.
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  • Acids Compounds that release hydrogen ions (H+) into a solution. Acids have a pH between 0-6
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  • Bases Compounds that release hydroxide ions (OH-) into a solution. Bases have a pH between 8-14
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  • Neutral strong acid (H+) + strong base (OH-) = water and salt. pH of 7
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  • Buffers Weak