Presentation on theme: "Chapter 2 Lecture Outline See PowerPoint Image Slides"— Presentation transcript:
1 Chapter 2 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted intoPowerPoint without notes.
2 Matter, Energy, and LifeMatter is anything that has mass and occupies space.Energy is the ability to do work.There are two types of energy:Potential energyStored energy, available to do workKinetic energyEnergy of motionPotential energy can be converted to kinetic energy to do work.
3 Law of Conservation of Energy Energy is never created or destroyed.The first law of thermodynamicsEnergy can be converted from one form to another, but the total energy remains constant.An object at the top of a hill has potential energy based on its location.When the object rolls down the hill, the potential energy is converted to kinetic energy.
4 Forms of Energy There are five forms of energy: Mechanical energy Energy of movementNuclear energyEnergy from reactions involving atomic nucleiElectrical energyFlow of charged particlesRadiant energyEnergy in heat, light, x-rays, and microwavesChemical energyEnergy in chemical bonds
5 What Is the Nature of Matter? AtomsThe smallest units of matter that can exist separatelyElementsChemical substances composed of the same kind of atomsListed on the periodic tableEach element is represented by a symbol of one or two letters.The principal elements that comprise living things are:C, H, O, P, K, I, N, S, Ca, Fe, and Mg.
7 Atomic Structure Atoms are composed of: The atomic nucleus Electrons: Protons - positively chargedAtomic number - the number of protonsAll atoms of the same element have the same number of protons.Neutrons – no chargeElectrons:Orbit the nucleus in energy levels.Are constantly in motion.
9 ElementsAtoms of the same element have equal numbers of electrons and protons.Thus, they have a neutral charge.IsotopesAtoms of the same element that have different numbers of neutronsAtomic weight - the average of all of the isotopes in a mixtureMass numberThe sum of protons and neutrons in the nucleus
11 Electrons Electrons occupy specific energy levels around the nucleus. Electrons closest to the nucleus have the lowest energy.Energy levels hold specific numbers of electrons.The first energy level can have up to 2 electrons.All other energy levels can have up to 8 electrons.Atoms seek to have a full outer energy level.Atoms that have full outer energy levels are inert.Other atoms seek to fill their outer energy levels through chemical bonds.
13 The Formation of Molecules Molecules consist of two or more atoms joined by a chemical bond.A compound is a chemical substance made of two or more elements combined in chemical bonds.The formula of a compound describes the nature and proportions of the elements that comprise the compound.H2O
14 Molecules and Kinetic Energy Molecules are constantly in motion.Temperature is a measure of the average speed of the molecules in a substance.The greater the speed, the higher the temperature.Measured in Fahrenheit or CelsiusHeat is a measure of the total kinetic energy of molecules.Measured in calories (amount of heat that will raise 1g of water 1 degree Celsius).Heat and temperature are related.Add heat energy to a substance and the molecules will speed up, and the temperature will rise.
15 Kinetic Energy, Physical Changes, and Phases of Matter Three phases of matter:SolidLiquidGasThe phase in which a substance exists depends on its kinetic energy and the strength of its attractive forces.Solids-strong attractive forces, low kinetic energy, little to no molecular movementLiquid-enough kinetic energy to overcome the attractive forces; more molecular movementGas-high kinetic energy, little to no attractive forces; maximum movement
16 Chemical Changes—Forming New Kinds of Matter Chemical reactionsCreating different chemical substances by forming and breaking chemical bondsRemember: Atoms form chemical bonds to fill their outermost electron energy levels, achieving stability.There are several types of chemical bonds.We will discuss:Ionic bondsCovalent bonds
17 Ionic BondsAtoms can gain or lose electrons to achieve a full outermost energy level.Atoms with charge are called ions.When an atom gives away an electron, it ends up with more protons than electrons and gains a positive charge; cation.When an atom accepts an electron, it ends up with more electrons than protons and gains a negative charge; anion.This process is called ionization.An ionic bondThe attraction between oppositely charged ionsExample: NaClSodium (Na) has one electron in its outer energy level.Chloride has seven electrons in its outer energy level.Sodium donates an electron to chloride, each achieving stability.The positively charged sodium is attracted to the negatively charged chloride.
19 Covalent BondsAtoms can achieve full outermost energy levels by sharing electrons instead of exchanging them.A covalent bond is formed by the sharing of electrons.The atoms sharing electrons sit close enough together so that their outer energy levels overlap.Single covalent bond- one pair of electrons is shared.H2Double covalent bond- two pairs of electrons are shared.ethyleneTriple covalent bond- three pairs of electrons are shared.N2
21 Hydrogen BondsThe positive hydrogen end of one polar molecule is attracted to the negative end of another polar molecule.This attraction is a hydrogen bond.Hydrogen bonds hold molecules together.Since they do not hold atoms together, they are not considered true chemical bonds.Hydrogen bonds are very important in biology.They stabilize the structure of DNA and proteins.Water molecules can “stick” together with hydrogen bonds.
22 Water: The Essence of Life Water has special properties that make it an essential molecule for life.H2OElectrons are shared unequally by hydrogen and oxygen.This is a polar covalent bond.Oxygen has more protons than hydrogen.The electrons spend more time around oxygen than around hydrogen.The oxygen end of water is more negative.The hydrogen end of water is more positive.
24 Mixtures and Solutions A mixtureMatter that contains two or more substances that are not in set proportionsA solution is a homogeneous mixture of ions or molecules of two or more substances.Components are distributed equally throughout.The process of making a solution is called dissolving.The solvent is the substance present in the largest amount.Frequently the solvent is a liquid.The solutes are the substances present in smaller amounts.Aqueous solutions are solids, liquids, or gases dissolved in water.
26 Water and LifeThe following properties of water make it essential for life:High surface tensionWater molecules stick to each other via hydrogen bonds.Capillary action moves water through streams, soil, animals, and plants.High heat of vaporizationA lot of heat is required to break the hydrogen bonds holding water together.Large bodies of water absorb a lot of heat.Temperate climatesEvaporative cooling
27 Water and Life Unusual density properties The universal solvent Ice is less dense than water, so ice floats.Allows aquatic life to survive in cold climates.The universal solventWater can form hydrogen bonds with any polar or ionic compound.Therefore, many things can be dissolved in water.
28 Chemical Reactions A chemical change: When the bonds of compounds are made or broken, new materials with new properties are produced.Happens via chemical reactions.In a chemical reaction the elements remain the same, but the compounds they form and their properties are different.
29 Chemical Reactions and Energy Chemical reactions produce new compounds with less or more potential energy.Energy is released when compounds are made with less potential energy.Energy is used to make compounds with more potential energy.
30 Chemical EquationsA chemical equation is a method of describing what happens in a chemical reaction.For example, photosynthesis is described by the following equation:Energy + 6CO2 + 6H2O → C6H12O6 + 6H2OReactants-substances that are changed, usually on the left side of the equationProducts-new chemical substances formed, usually on the right side of the equation
31 Five Important Chemical Reactions in Biology Oxidation–reductionDehydration synthesisHydrolysisPhosphorylationAcid–base reactions
32 Oxidation-Reduction Reactions Reactions in which electrons (and their energy) are transferred from one atom to another.OxidationAn atom loses an electron.ReductionAn atom gains an electron.For oxidation to occur, reduction must also occur.Example:RespirationSugar is oxidized to form carbon dioxide and oxygen is reduced to form water.Energy is released in the process.C6H12O6 + 6O2 → 6H2O + 6CO2 + EnergySugar + oxygen → water + carbon dioxide + energy
33 Dehydration Synthesis Reaction When two small molecules are joined to form a larger molecule,A molecule of water is released.Example:Joining amino acids to form proteinsNH2CH2CO-OH + H-NH CH2CO-OH NH2CH2CO-NH CH2CO-OH + H-OHamino acid amino acid = protein water
34 Hydrolysis ReactionsWhen a larger molecule is broken down into smaller parts:A water molecule is splitOpposite of a dehydration synthesisExample:Digesting proteins into amino acids.NH2CH2CO-NH CH2CO-OH + H-OH NH2CH2CO-OH + H-NH CH2CO-OHProtein water = amino acid amino acid 2
35 Phosphorylation Reactions When phosphate groups are added to other molecules,Phosphate groups are clusters of oxygen and phosphate atoms.Bonds between phosphate groups and other molecules contain high potential energy.When these bonds are broken, the energy that is released can be used by the cell to do work.Phosphorylation reactions are commonly used to transfer potential energy.Q-P + Z Q + Z-P
36 Acid-Base ReactionsOccurs when ions from an acid interact with ions from a baseThis type of reaction allows harmful acids and bases to neutralize one another.H+Cl Na+OH- → Na+Cl- + H+OH-Hydrocloric + Sodium Sodium Wateracid hydroxide chloride
37 Acids, Bases, and Salts An acid A base Ionic compounds that release hydrogen ions (H+) into a solutionPhosphoric acid, hydrochloric acidA baseCompounds that release hydroxide ions (OH-) into a solutionSodium hydroxide, ammoniaBecause bases are negatively charged, they will react with a positively charged hydrogen in solution.The strength of an acid or base is determined by how completely it will dissociate in water.Strong acids release almost all of their hydrogen ions into water.Strong bases release almost all of their hydroxide ions into water.
39 Salts Neither acids nor bases Usually formed when acids and bases reactThe dissociated hydrogen ions and hydroxide ions join to form water.The remaining ions form ionic bonds, creating a salt.This is an example of neutralization:H+Cl Na+OH- → Na+Cl- + H+OH-Hydrocloric Sodium Sodium Wateracid hydroxide chloride
40 pH A measure of hydrogen ion concentration Solutions with high hydrogen ion concentrationsHave low pHAre acidicSolutions with low hydrogen ion concentrationsHave a high pHAre basicThere is a 10-fold difference in hydrogen ion concentration between solutions that differ by one pH unit.A solution with pH 4 has ten times as many hydrogen ions as a solution with pH 5.
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43 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at
44 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at
45 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at