Like the author’s other companion books, The Chemistry Companion provides high quality information in unique one-page-per-topic presentations that not overburden and distract readers with excessive details The book offers concise summaries of general chemistry concepts, easily accessible in a convenient, reader-friendly format Suitable as an introduction or study guide, this companion presents the minimum of what readers need to know to understand the subject It emphasizes the physics underlying chemistry By looking at chemistry processes from a physics point of view, readers better appreciate what is happening from the chemical perspective that is usually found in traditional chemistry books The author focuses on the structure of matter, chemical components and bonds, the periodic table, states of matter, thermodynamics, reaction rates, carbon chemistry, biochemistry, and chemical, ionic, and electronic equilibria Each topic is covered in a single-page outline format with just enough detail to enable a good understanding of the subject • Provides a physical understanding of chemical concepts • Presents clear explanations of difficult material, working through any inconsistencies in understanding • Uses a convenient format for checking formulas and definitions • Includes self-contained information on each page, assuming little prior knowledge OCH3 C H A C FISCHER-CRIPPS Features The Chemistry Companion Chemistry The Chemistry Companion K11517 ISBN: 978-1-4398-3088-8 90000 781439 830888 O A C FISCHER-CRIPPS The Chemistry Companion This page intentionally left blank The Chemistry Companion A C FISCHER-CRIPPS CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2012 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S Government works Version Date: 20110517 International Standard Book Number-13: 978-1-4398-3089-5 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint Except as permitted under U.S Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers For permission to photocopy or use material electronically from this work, please access www copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400 CCC is a not-for-profit organization that provides licenses and registration for a variety of users For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com This book is dedicaated to Bill Cripps industriaal chemist This page intentionally left blank vii Contents Preface ………………………………………………………………… xiii Structure of Matter 11 1.1 Atoms 2 1.2 Bohr Atom .3 1.3 Energy Levels 1.4 Schrödinger Equation 1.5 The Infinite Square Well 1.6 The Coulomb Potential 1.7 Covalent Bond .8 1.8 Ionisation Energy 1.9 Electron Affinity 10 1.10 Ionic Bond 11 1.11 Electronegativity 12 1.12 Metallic Bond .13 13 Electronic Structure of Solid 1.13 ds 14 Chemical Components .15 2.1 Matter 16 2.2 Atomic Weight 17 2.3 Ions 18 2.4 Molecules 19 2.5 Mole 20 2.6 Compounds 21 2.7 Cations 22 2.8 Anions 23 2.9 Chemical Equation 24 10 Stoichiometry .25 2.10 25 2.11 Example 26 The Periodic Table 27 3.1 Electron Configuration .28 3.2 Periodic Law 29 3.3 Periodic Table .30 3.4 Groups .31 3.5 Energy Levels 32 3.6 Noble Gases 33 3.7 Atomic Size 34 3.8 Covalent Radii 35 39 3.9 Ionic Radii Radii 36 36 3.10 Ionisation Energy .37 3.11 Electronegativity 38 viii Chemical Bonds 39 4.1 Chemical Bond 40 42 4.2 Lewis (Electron Dot) Formulae 41 4.3 Multiple Bonds 42 4.4 Lewis Single-Bonded Structtures 43 4.5 Lewis Multiple-Bonded Structures 44 4.6 Lewis Exceptions to the Octtet Rule 45 4.7 Oxidation Number 46 es 47 4.8 Oxidation Number Example 4.9 Polar Bonds 48 4.10 Hybrid Orbitals 49 4.11 Polarisation 50 4.12 van der Waals Forces 51 4.13 Hydrogen Bond 52 States of Matter 53 5.1 Changes of State .54 5.2 Changes of State of Liquidss/Gases 55 5.3 Phases of Matter 56 5.4 Gases 57 5.5 Solutions 58 5.6 Aqueous Solutions 59 5.7 Solubility of Solids 60 5.8 Solubility Equilibrium 61 5.9 Electrolytes 62 5.10 Osmosis 63 11 Solids 64 5.11 64 5.12 Crystalline Lattice Structure es .65 5.13 Metallic Solids 66 Chemical Thermodynamics 67 6.1 Molecular Energy .68 6.2 Specific Heat Capacity 69 6.3 Enthalpy .70 6.4 Heat of Reaction 71 6.5 Heat of Reaction 72 6.6 Enthalpy of Formation 73 6.7 Entropy 74 68 6.8 Entropy Calculations 75 75 6.9 Gibbs Energy .76 6.10 Spontaneous Processes 77 6.11 Melting of Ice 78 6.12 Freezing of Water 79 ix 6.13 6.14 15 6.15 Ice/Water Equilibrium 80 Chemical Equilibrium 81 Statistical Entropy 82 82 Rates of Reaction 83 7.1 Rates of Reaction 84 7.2 Collision Theory 85 7.3 Reaction Mechanism 86 7.4 Activation Energy 87 7.5 Nature of Reactants 88 7.6 Concentration 89 7.7 Rate Law 90 7.8 Rates of Reactions 91 7.9 Determination of Order 92 10 Determination of 1st Order R 7.10 Rate Law 93 7.11 Half-Life Method 94 7.12 Temperature 95 7.13 Catalysts 96 Chemical Equilibrium 97 8.1 Chemical Equilibrium 98 8.2 Law of Chemical Equilibrium m 99 8.3 Equilibrium Constant 100 8.4 Le Chatelier’s Principle 101 8.5 Summary of Le Chatelier’s Principle P 102 8.6 Equilibrium in Gaseous Sysstems 103 87 8.7 Solubility of Solids .104 104 8.8 Factors Affecting Equilibrium m 105 8.9 Common Ion Effect 106 8.10 Precipitation .107 8.11 Complex Ions 108 Ionic Equilibrium 109 9.1 Electrolytes 110 9.2 Ionisation of Water 111 9.3 H+ and OH Concentrationss .112 9.4 Acids and Bases 113 9.5 BronstedLowry 114 96 9.6 Strength of Acids 115 9.7 AcidBase Reactions 116 9.8 Buffer Solutions 117 9.9 Indicators 118 9.10 Neutralisation 119 162 The Chemistry Companion 12.1 Sugars Sugars are part of a larger group of compounds called carbohydrates Carbohydrates have the general formuula Cm (H2O)n and can be thought of as hydrated carbon compounds Glucose, C6H12O6, Fructose, an isomerr These compounds can readily form an important sugar of glucose, C6H12O6, cyclic structures, which are often in biochemistry is an and is a ketone more common than the chain aldehyde structures H O CH2OH Glucose and fructose are examples C of monosaccharides Sucrose, or C O table sugar, is a disaccharide and is H C OH formed by the condensation (with H C OH H OH C the elimination of one water H OH C molecule) l l ) off one molecule l l off H OH C fructose and one of glucose The H OH C reverse reaction, hydrolysis of H OH C sucrose, splits sucrose into glucose CH2OH H CH2OH and fructose H C OH C H C HO Glucose C HO O H OH H C H H H OH H C H H C Fructose O H C C H H HO C C C OH OH H OH HO O OH O H OH H C H H H C C C H O H H H HO C C C OH OH H O OH C Sucrose OH C H C H C C OH H H2O Glucose is the basic fuel for thee process of metabolism Glucose is recovered from fats and sugars in the diet and stored as glycogen in the body until converted back to glucose for usee directly by cells 12 Biochemistry 163 12.2 Polysaccharides Cellulose is a straight-chain poly ysaccharide (C6H10O5)n consisting of thousands of glucose units It is insolluble in water The nature of particular forms of cellulose in organisms depennds mainly upon the chain length of the molecule Hydrogen bonding H H C H C O C H H OH C O HH H OH H C C H OH C C C O Cellulose between parts of the molecule impart strength to the structure OH O H H OH H C C H OH Starch is similar to cellulose in that it is constructed from glucose monosacchaaride units, but has a different orientation of o linkage between the glucose elements, with w more branching than cellulose It is geenerally a mixture of glucose polymers of varyinng lengths, the shorter constituents (of molecular weight 4000) being water soluble Starch typically contains a mixturee of linear (soluble) amylose and branched (relatively insoluble) amylopectin molecules Complete hydrolysis gives glucose Partial hydrolysis results in various starch sugars called dextrins Starch is broken down into glucose in i the body by enzymes, (chiefly amylase, which w is a constituent of saliva and pancreatic juuice) Glycogen is similar to the amylopectin form of starch in structure and is found inn the liver and muscles of animals as an energy store It is y from gglucose from digggestion by y synthesised enzymes in the liver where it is sttored until released as glucose into the blooddstream as needed C O Cellulose acts as the main structural element of plants and forms the cell wall that gives plants their rigidity Wood is about 50% cellulose Mammals generally are incapable of breaking down cellulose to glucose although cows and sheep, and other ruminants, have the necessary bacteria in their di digestive ti system t th thatt perform this function Insects (e.g termites) can also digest cellulose Starch is used as an energy store in plants The glucose produced by photosynthesis is stored in plant tissue as starch until it is needed by the plant Starch in plants, when eaten as food, is an important source of glucose l ffor animals i l 164 The Chemistry Companion 12.3 Lipids Fats and oils are esters Esters are derrivatives of carboxylic acids where the H on the OH group is replaced by R so s that the general formula is RCOOR' Esters are usually derived from the reeaction between acids and alcohols with the elimination of a water molecule Fat in the body acts as a storage place for Animal and plant fats are C OH CH glucose When fat triple esters, or triglycerides, reserves are called upon, of glycerol (glycerin) C3H8O3 OH C CH the fats are converted Each of the three available OH back into glycerol and C OH CH fatty acids The glycerol groups in glycerol is available in turn is converted into for combination with three G Glycerol glucose by the liver molecules of fatty acid Fatty (propaane 1,2,3 triol) Fats in the diet are also a acids typically have from 12 to source of linolenic 20 carbon atoms atoms C17H29CO2H and linoleic Fats, which are solid at room tempeerature, are C17H31CO2H unsaturated made from saturated fatty acids, while w oils, fatty acids which are essential in animal which are liquid at room temperrature, are dietary intake because formed mainly from unsaturated faatty acids they are unable to be Fats and oils from plants and animals typically synthesised by the body contain a mixture of different types of esters, directly and are required for metabolism into a two or three fatty acids attached to a glycerol variety of other acids molecule required by various bodily functions Linolenic acid has the general form mula CH3(CH2)4CH=CHCH2CH=CH(CH2)7CO OOH and is called an omega-6 fatty acid because the first C=C double bond is on the sixxth carbon atom from the (left-hand) end Linoleeic acid is am omega-3 acid (Note: normally nuumbering of atom positions is from the right.) CH3CH2CH=CHCH2CH=CHCH2CH2=CH(C CH2)7COOH Linoleic acid Fats, along with oils and waxes, are one o lipids example of a broader group of Compared p to carbohydrates, y , lipids p generally g y contain a smaller proportion of O atom ms Lipids are relatively insoluble in water Fats also serve a structural role in the body by providing heat insulation and a barrier against mechanical shock for organs When fats hydrolyse, or react with water, in an alkaline solution, glycerol is formed along with the metal salt of the carboxylic acid Such a reaction is called saponification, from which soaps (e.g sodium stearate) is formed 12 Biochemistry 165 12.4 Proteins Proteins are amino acids joined togeth her by amide (or peptide) links and are classified as polyamides The arranngement, or sequence, of amino acids within the protein structure determinees the function of the protein A typical protein may contain 100 or more aminno acids The mechanical structure of proteins (i.e the Amino acids with the O sequence of amino acids amine group attached to the R CH C and hydrogen bonds) has same C atom as the COOH OH great significance for NH2 group are called alphaliving organisms Proteins form the basis of skin, amino acids and are the mino acid am hair, muscle, tendons, most important in and other tissues in the biochemistry body The twenty or so amino acids foundd in proteins Some proteins are diff in differ i the th makeup k off the th R residual id l In I enzymes and act as glycine, R is just an H atom, while in catalysts for chemical reactions which would phenylaniline, R is a ring structure otherwise proceed too On one end of the chain, there is a free NH2 slowly for use in o end of organisms group; this is the N terminal At the other the chain, there is a COOH grooup, the C The secondary structure terminal In between, water moleculess have been of proteins is stable eliminated to leave amino acid units, or o residues within narrow R NH2 C N H H O R C C H N H O R C C COOH H A typical polypeptide protein consists c of between 100 and 500 or more amino a acid residues The sequence of amino acids a is the primary structure of the molecule The long chains of proteins themselves have a secondary structure, usually in the form of a helix or spiral Hydrogen bonds betweenn different amino acid groups are responsiblle for this structure Often, there is more than one polypeptide p yp p chain ppresent and they exist as intertwined helixes held together by hydrogen h or ionic bonds leading to a tertiary struccture When a protein undergoes complete hydrolysis, the amino acids are recoveered temperature and pH ranges When the secondary structure of a protein is disrupted, either by heat (such as by cooking), or immersion in acids or alkalis, the protein is said to be denatured and the physical properties change markedly 166 The Chemistry Companion 12.5 Nucleic Acids Carbohydrates, lipids and proteins maake up the bulk of living organisms A fourth major class of compounds com mprise the nucleic acids DNA and RNA Nucleic acids are long-chain polyymers that consist of smaller units, nucleotides, joined together base phosphate In DNA, there are four group OH OH types of nucleotide nucleotide N P Each nucleotide H H O consists of a 5-carbon OH water O OH H HO C sugar (deoxyribose), lost sugar with an attached phosphate, C C H H and a nitrogen base Each type wateer lostt H H is distinguished by the identity C C of the nitrogenous bases bases OH H In DNA, there are only four bases prresent O DNA bases H3C NH2 N NH N HC HC CH A N H N adenine T O N H thymine O NH2 N NH N HC HC N H G N guanine NH2 HC C Nucleotide phosphate O sugar OH base N H cytosine The NH group on the base combines with the OH group on the sugar and a H2O is lost The primary structure of DNA is a sequence of nucleotides bonded together as long chains The phosphate group of one nucleotide bonds with the sugar of another (losing a molecule of water in the process) O A shorrthand way off writing these groups is to justt show the covale ent bonds between the groups s, and leave out the C and H atoms O O O 12 Biochemistry 167 12.6 DNA The primary structure of DNA is esssentially the sequence of bases in the nucleotides in the chain However, DN NA does not ordinarily exist as a single chain, but is paired with an opposite chain so that the bases are paired and held together by hydrogen bonds The bases can only O A = T pair according to certain rules: A is always paired with T by a double hydrogen O C G bond G is always paired with C by a triple hydrogen bond O O O The ladder-like Th l dd lik T = A structure is further characterised by being coiled up in a O spiral, each chain with C G bases pointing inwards and bonding with the corresponding base on the other – the so-called double-helix The nucleotides, identified by their bases, can appear in any particular order, but the sequence on one chain has to be reflected in the other by virtue of the base-pairing rules A-T and G-C Although there are only four Sequences of nucleotides fall into bases in human DNA, the functional groups called genes, whicch in molecule typically consists of turn lie along a single large DNA D about 1500 nucleotides in the molecule called a chromosome In most chain, allowing billions of combinations of base cells, chromosomes occur in dupliccated sequences possible in a single pairs When cell division by miitosis molecule occurs, the DNA molecules are repliccated RNA is similar to DNA but by rupturing the hydrogen bonds betw ween consists of ribose as the sugar the two chains and then each chain c and a single chain structure with forming bonds with new nucleootides the base uracil rather than thymine y There are different according to base base-pairing pairing rules When n cell types of RNA; some act as division is complete, the two new cells messengers, carrying the DNA each contain paired chromosomes of the template to the site of protein same genetic sequence as the parent cell synthesis (ribosomes) in the O O cell, while others transport amino acids to the ribosomes 168 The Chemistry Companion 12.7 Enzymes The many chemical reactions which take t place in an organism to sustain life are collectively called metabolism Typical T reactions are condensation and hydrolysis reactions: polysaccharides sugars fatty acids + glycerol amino acids ondensation Co Hydrolysis (cellulose, starch) fats proteins These reactions occur at temperaturres of about 37C under atmospheric pressure The reaction rates would be b too slow unless reaction pathways were altered by use of catalysts Neaarly every biological chemical reaction involves the use of a specific biological catalyst called an enzyme Enzymes are very large protein mollecules of a specific shape The enzyme molecule is typically much larger thann the molecules actually involved in the chemical reaction The reaction mollecule (or molecules in the case of a condensation reaction), called the subbstrate, attaches itself to an active site on the enzyme molecule products substra ate Enzyme/ An activated complex substrate is formed, and the complex reaction proceeds along a different pathway than would normally occur in enz zyme enzyme enzyme the laboratory When the reaction is complete, the products detach from the enzyme and the enzyme is available to catalyse anoother reaction Enzymes lower the activation energgy by increasing the collision frequency of molecules by virtue of bringing the molecules together spatially in an optimum manner, or altering the bonnd energies involved in the reaction by forming temporary bonds on the reacting molecules, and in some cases, applying mechanical stress to the reaccting molecules to facilitate contact Enzyme inhibitors are used within n the organism to control the activity of enzymes by masking or blocking the active sites on the enzyme to regulate reaction rates as a whole The importance p of enzymes y cannoot be over-stated In a livingg cell,, the reagents of all the chemical reactions are not stored in isolated bottles and mixed when needed as in a laboratoryy, but exist all together in solution The process of chemical reactions betweeen these mixed reagents is orchestrated by the action of enzymes 12 Biochemistry 169 12.8 ATP Organisms need nutrients to stay aliive Nutrients comprise carbohydrates, proteins and fats and, in animals, arre usually ingested as food Nutrients provide a source of energy, essentiall amino acids and essential fatty acids Vitamins and other trace elementts are also required for the proper functioning of enzymes Metabolism is the oxidation of glucoose to carbon dioxide, water and energy: C H12 O 6O 36ADP 36P 6CO 6H O 36ATP The energy released by the oxidationn process Energy stored as is stored as chemical potential energgy in the phosphate bonds via the formation of ATP molecules from m ADP conversion of ADP molecules Adenosinediphosphate consists (adenosinediphosphate) to ATP of a molecule of adenine, ribose, and two (adenosinetriphosphate) phosphate groups: ADP P energy ATP H O H2N N N ribose OH CH2 OH O P O P O P = adenine N = N O O O O = CH HC O O O OH phosphates When energy is used to bind a thiird phosphate group to the end of the molecule, adenosinetriphosphate is formed f This is an endothermic process and is called phosphorylation The energy e used to create ATP is stored in the phosphate bond Energy-rich AT TP molecules are then hydrolysed to release their energy when used directly in other biological processes such as n impulse transmission muscle action, protein synthesis and nerve Another important molecule invollved in metabolism is the co-enzyme NAD (nicotinamide adenine dinucleotide phosphate) NAD takes part in oxidation-reduction reactions in metabolism m by losing and accepting electrons ultimately necessary for coonversion of ADP to ATP The redox reactions are NAD 2H 2e NADH H reduction NADH H NAD 2H 2e oxidation Reduction can occur by adding hydrogen Oxidation can occur by y removing hydrogen When NAD+ is reduced, it stores enerrgy by storing an excited electron in the form of NADH and a H+ ion Wheen NADH+H+ is oxidised, it releases energy, usually to form ATP from AD DP 170 The Chemistry Companion 12.9 Anaerobic Metabolism Anabolic processes build up low-enerrgy reactants into high-energy products Photosynthesis in plants is an anabollic process Catabolic processes break down high-energy reactants to low energy products, releasing energy in doing so This energy is transferred too ATP Anaerobic metabolism involves tw wo steps: (i) the breakdown of glucose from a carbohydrate into pyruvic accid: C H12 O NAD 4ADP 2C H O NADH 2H 4ATP and (ii) the fermentation of pyruvic acid a into either CO2 and ethanol, or lactic acid The ultimate aim is to prodduce ATP from ADP Glycolytic pathway e.g glucose, from a carbohydrate C6 Energy is absorbed in this preparatory step glycolosis 2ATP 2ADP PGA AL (phosoglyceraldehyde) 2NAD+ fermentation No O2 present 2NADH+2H+ 4ADP 4ATP 2NADH+2H+ C3 2NAD+ CO2 + ethanol (plants) Lactic acid (animals) Energy is released and stored in ATP Pyruvic acid if O2 present (2) of aerobic metabolism (1) of aerobic metabolism Net ATP gained Anaerobic metabolism occurs in all a cells It does result in a particularly high yield of ATP since the productss, ethanol, lactic acid and pyruvic acid, still contain a substantial portion of the original energy from the glucose While anaerobic metabolism can proovide ATP for energy use (in muscles) when O2 is in short supply, or nonne at all, it also provides a source of pyruvic acid for use in aerobic respirration 12 Biochemistry 171 12.10 Aerobic Metabolism from glycolysis Aerobic metabolism, or respiration n, is the process by which glycerol is oxidised with the production of ATP molecules from ADP molecules in the presence of molecular oxygen: 2NADH 2H O NAD 2H O (1) C2 Coenzyme A (2) + ATP 2C 2CoA NAD 2AceetylCoA NADH 2H 2CO Pyruvic acid (3) (4) 2N NADH 2H O NAD 2H O 2AcetylCoA Krebs cycle CO H O + ATP directly + NADH+H+ + ATP (1) The NADH from glycolysis is ox xidised, by the addition of O2, to produce sixx ATP (2) Pyruvic acid C3 is oxidised to ann activated form of acetic acid C2 NAD+ is reduced to NADH+H+ (3) NADH+H+ from (2) is oxidised by b O2, to form six ATP (4) AcetylCoA enters the Krebs cyccle (or citric acid cycle) This consists of multiple reactions, the net effeect of which is to form two molecules of ATP plus energy-rich NADH During the Krebs cycle, six moleculles of NADH+H+ and two molecules of a related compound, FADH, are form med These electron-carrier molecules are energy-rich and can be further oxxidised as in (1) and (3) which require O2 The net result of (4) is the prodduction of twenty two ATP molecules Anaerobic metabolism produces two o molecules of ATP, which added to the thirty four ATP molecules from aerobic a metabolism makes thirty six molecules of ATP from the complete oxidation o of one molecule of glucose Fats and proteins Protein Amino acids Fats Glycerol Fatty are also sources of acids ATP, by virtue of Pyruvic PGAL their breakdown Acetyl acid into components CoA which can be to to glycolytic l l tic i inserted d i into to (4) of glycolytic pathway y glycolytic and aerobic pathway pathway aerobic pathways 172 The Chemistry Companion 12.11 Cyclic Photophosphoryylation Ultimately, the energy contained withhin glucose used in animal metabolism comes from photosynthesis in plantss The overall reaction in plants, for the production of glucose, is Note that O2 is a light product of this reaction 6CO 12H O Energy C H12 O 6O 6H O Chlorophyll is the unique ingredien nt of plants that captures photons to promote an electron of low energy intto an excited state The excited electron is passed from one transfer molecule to another, losing energy at each step, until it returns to a chlorophyll moleccule in an unexcited state At each step, the energy lost is used to convert ADP P to ATP: ADP P Energy ATP H O As the excited electron is passedd from molecule to molecule, some of the ennergy is used to create ATP The process is noot 100% efficient 2e PQ E = hv Cyt energy PC Chlorophyll ADP ATP Because electrons are donated by chlorophyll from the high-energy state and then to acceptance in a lowenergy state, this synthesis of ATP is called cyclic photophosphorylation The ATP, essentially created from ADP by the energy of sunlight, is ultimately used to create high energy glucose high-energy (which is stored in the plant as starch) from low-energy CO2 Animals eat the plants and convert starch into glucose, which is then used to create ATP for their own metabolic processes PQ, Cyt and PC are electron carrier molecules that undergo reduction (whhen they accept the electron) and oxidation (whhen they donate the electron) In this mode of photophosphorylationn, electrons are transported around in a cycle; no oxygen or NADH+H+ is prooduced 12 Biochemistry 173 12.12 Non-Cyclic Photophosphorylation Another way of producing ATP usedd by plants has a beginning similar to cyclic photophosphorylation, but em mploys a more complicated path for extraction of energy from exxcited electrons This non-cyclic photophosphorylation is used by modeern green plants : 4e Fd to dark reactions to make glucose Fp 2NAD 4H 4e NADH 2H E = hv 4e 2ADP 2ATP (stored energy) Cyt Chlorophyll PC 4e 4e PQ E = hv 4e Chloro ophyll 2H O 4H O 4e 3ATP 3ADP The production of ATP and NADH+ +H+ involves two light reactions Electronn deficiency in one Note that O2 is a chlorophyll is balanced by different ellectrons from those product of this reaction from the water dissociation Additional reactions take pplace in which w the energy gy obtained from the light g reactions is converted into carbohydraates for storage That is, CO2 is reduced, +) the NDAH+H+ is oxidised and (if the energy is coming from NADH+H N with the net result being glucose Theese are known as dark reactions since no light is required The resulting glucose is used in Ribulose metabolism by the plant cells 3C5 + 3CO2 for making cellulose/starch (trunks and branches, etc) and 3C6 other sugars (such as in fruit), 6ATP 6ADP which may in turn be eaten by 6PGA animals from which the glucose ((2C3 + P)) + + is recovered and used in animal 6NADH+6H 6NAD 6PGAL metabolism 5PGAL 1PGAL C6H12O6 (glucose) stored as starch 174 The Chemistry Companion 12.13 Metabolism Summary: Food Proteins Carbohydrate es Air Fats O2 Eating Breathing Digestion Amino acids Glucose Glycerol Fatty acids Glycogen Oxygen Fat Proteins Anaerobic and d aerobic metabolism CO2 ATP Also required are vitamins (organic compounds in small quantities that cannot be synthesised by the body) and minerals (usually absorbed as metal ions) Vitamins and minerals are required as components of enzymes, y , muscle action, bones, teeth, haemoglobin, etc ATP is used to provide the energyy source for conversion of amino acids into proteins required by the body for f the production of skin, hair, cells, enzymes, muscles, nerves, signallingg, anaerobic respiration, as well as for energising DNA replication It alsoo provides energy for muscle action, vision, brain activity, and nearly all a biological energy transformations Glycogen and fats can be stored in the body and sent back into the metabolism pathway as glucose andd glycerol for oxidation into CO2 and energy when h there th is i no food f d being b i digested t d This page intentionally left blank Like the author’s other companion books, The Chemistry Companion provides high quality information in unique one-page-per-topic presentations that not overburden and distract readers with excessive details The book offers concise summaries of general chemistry concepts, easily accessible in a convenient, reader-friendly format Suitable as an introduction or study guide, this companion presents the minimum of what readers need to know to understand the subject It emphasizes the physics underlying chemistry By looking at chemistry processes from a physics point of view, readers better appreciate what is happening from the chemical perspective that is usually found in traditional chemistry books The author focuses on the structure of matter, chemical components and bonds, the periodic table, states of matter, thermodynamics, reaction rates, carbon chemistry, biochemistry, and chemical, ionic, and electronic equilibria Each topic is covered in a single-page outline format with just enough detail to enable a good understanding of the subject • Provides a physical understanding of chemical concepts • Presents clear explanations of difficult material, working through any inconsistencies in understanding • Uses a convenient format for checking formulas and definitions • Includes self-contained information on each page, assuming little prior knowledge OCH3 C H A C FISCHER-CRIPPS Features The Chemistry Companion Chemistry The Chemistry Companion K11517 ISBN: 978-1-4398-3088-8 90000 781439 830888 O A C FISCHER-CRIPPS ... attracted to the same two electrons Therefore, the two nuclei n behave as if they were bonded together The co-sharing of these valence electrons and the resulting attraction of the two atoms... the ions are formed, the atttraction between them causes them to move towards each other and the electrical potential between them drops The ions reach an equilibrium distance determined by the. .. stability – that is, the free electrons e in the valence band reduce the energy of the system and so act to holld the two atoms together This is called a metallic bond 14 The Chemistry Companion 1.13