bluuebunny/crossref_metadata_2025 huggingface dataset:
Benthic Life Habits
Authors: Levinton Jeffrey S.
Published: September 2023

This chapter focuses on benthic life habits. It explains that epibenthic organisms survive attached to the surface and usually protrude into the flow. Since benthic animals are often collected and separated on sieves, a classification based on overall size is useful. Moreover, animals are divided into the feeding classification of deposit feeders, suspension feeders, herbivores, carnivores, and scavengers. It discribes the importance of sediments to benthic feeders. Organisms must adapt to strong laminar flow above the bottom, but they experience more complex flows near the surface, so epibenthic animals must have traits to minimize pressure drag by changing orientation.
Aerobic and Anaerobic Forms of Metabolism
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter details the aerobic and anaerobic forms of metabolism. It explains that both forms of metabolism are major categories of catabolic, biochemical pathways by which animal cells release energy from foodstuff molecules to synthesise adenosine triphosphate (ATP). The four mechanisms of ATP production are aerobic catabolism by the use of O2 acquired simultaneously from the environment, anaerobic glycolysis, anaerobic ATP production by the use of phosphagen, and aerobic ATP production by the use of internal O2 stores. The chapter also considers fatigue and muscle fibre types as the themes in exercise physiology. It cites the interplay of aerobic and anaerobic catabolism during exercise.
Thermal Relations
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter tackles the concept of thermal relations. It enumerates the key concepts related to the thermal reactions of animals: endothermy, thermoregulation, ectotherms, endotherms, homeotherm, and heterothermy. Temperature primarily refers to a measure of the speed of incessant random motions of molecules, while heat, in comparison, is merely a form of energy that a substance poses by virtue of random motions. The chapter then looks into the influence of temperature in fish and the impact of endothermy and homeothermy on insects. It mentions how endothermy can provide organisms with distinct advantages and evolve independently in animals and some plants multiple times.
Sensory Processes
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter provides an overview of sensory processes. It starts with the organisation of sensory systems in line with the classification of sensory receptor cells. Sensory systems provide animals with essentially all of the information they have about their external environment and their internal environment. Moreover, sensory systems of all kinds depend on specialised sensory receptor cells that respond to stimuli, either from the environment or arising inside the body. Sensory cells respond to different stimuli that vary greatly in sensitivity and specificity. The chapter then looks into the features and functions of vestibular organs, chemoreception, olfaction, photoreception, and visual sensory processing.
Reproduction
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter focuses on the process of reproduction among animals. The study of reproduction in physiology is primarily divided into the factors of adaptation and the mechanism, which are not exactly exclusive to each other. Additionally, the environment plays a large role in the process of reproduction. The chapter gives an overview of eggs, provisioning and parental care of animals. Many animal species have evolved mechanisms of decoupling successive steps in the reproductive process, so the mechanisms of sperm storage and embryonic diapause increase options of certain reproductive steps to coordinate with other steps. The chapter also shows how asexual reproduction occurs in some animals and can be important where it occurs.
Plasticity in Response to Use and Disuse
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter discusses the notion of movement and muscles in correlation with plasticity in response to use and disuse. It mentions how the phenotype of muscle tissue depends on the type of actions it performs. For example, motor units composed of different fibre types have different physiological characteristics. Muscle tissues support the ability to move and the capability of changing in terms of both mass and cellular characteristics. A muscle's activity of hypertrophy or atrophy causes interconversion between certain types of fibres. The chapter explains the importance of maintaining muscle mass to homeostasis, which references the balance between anabolic and catabolic processes in this crucial tissue.
External Respiration
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter considers the physiology of breathing. It explains how tunas breathe with their gills to illustrate the general principle of a single type of breathing system exhibiting a wide range of evolutionary refinements in various species. In all animals, the systems used to exchange respiratory gases with the environment consist of a gas-exchange membrane or respiratory-exchange membrane that separates the internal tissues of the animal from the environmental medium (air or water). External respiration or breathing is the process by which gas is transported to and away from the gas-exchange membrane from the environmental medium. The chapter details the principles of gas exchange by active ventilation.
Water and Salt Physiology of Animals in Their Environments
Authors: Hill Richard W. , Cavanaugh Daniel J. , Anderson Margaret
Published: September 2023

This chapter focuses on the water-salt physiology of animals in their environments. It explains that the teleost (bony) fish maintain their blood plasma at an osmotic pressure intermediate between that of freshwater and seawater. In terms of their water-salt physiology, animals have been versatile in adapting to an astounding range of environments on Earth. The chapter then considers the features of animals that face changes in salinity, animals on land, and animals responding to drying habitats. Moreover, the kidneys and other organs responsible for water and salt regulation in terrestrial animals are generally under hormonal control in both vertebrates and invertebrates.
Fertilization
Authors: Barresi Michael J. F. , Gilbert Scott F.
Published: September 2023

This chapter focuses on fertilization and relates it to sex and reproduction. It highlights the events of fertilization which include contact and recognition between sperm and egg, regulation of sperm entry into the egg, fusion of genetic material from the two gametes, and activation of egg metabolism to start development. It also describes eggs and their associated cells in plants or animals and shows how they secrete diffusible molecules to attract and activate the sperm. The chapter explores the two blocks to polyspermy: the fast block that is immediate, transient, and causes the egg membrane resting potential to rise and the slow block or cortical granule reaction that is physical, permanent, and is mediated by calcium ions. It shows the fusion of sperm and egg which causes re-initiation of the egg's cell cycle and subsequent mitotic division.
Intermediate and Lateral Plate Mesoderm
Authors: Barresi Michael J. F. , Gilbert Scott F.
Published: September 2023

This chapter talks about the intermediate mesoderm, which forms the kidneys, adrenal glands, and gonads and is specified through interactions with the paraxial mesoderm that require Pax2, Pax8, and Lim1. It describes the metanephric kidney of mammals which is formed by reciprocal interactions of the metanephric mesenchyme and a branch of the nephric duct called the ureteric bud. It also assesses the two layers of the lateral plate mesoderm: the dorsal layer, which underlies the ectoderm and forms the somatopleure, and the ventral layer, which overlies the endoderm and forms the splanchnopleure. The chapter reviews Tbx transcription factors that are critical for specifying the heart chambers. It looks into the hematopoietic stem cell (HSC) and shows how this depends on stem cell factor (SCF), which is provided primarily by the perivascular cells of the sinusoids contained in the stem cell niche.
The Biosphere
Authors: Bowman William D. , Hacker Sally D.
Published: September 2023

Key Concepts

CONCEPT 3.1 Terrestrial biomes are characterized by the growth forms of the dominant vegetation.

CONCEPT 3.2 Biological zones in freshwater ecosystems are associated with the velocity, depth, temperature, clarity, and chemistry of the water.

CONCEPT 3.3 Marine biological zones are determined by...
Production
Authors: Bowman William D. , Hacker Sally D.
Published: September 2023

Key Concepts

CONCEPT 20.1 Energy in ecosystems originates with primary production by autotrophs.

CONCEPT 20.2 Net primary production is constrained by both physical and biotic environmental factors.

CONCEPT 20.3 Global patterns of net primary production reflect climate constraints and biome types.

CONCEPT 20.4 Secondary...
Global Ecology
Authors: Bowman William D. , Hacker Sally D.
Published: September 2023

Key Concepts

CONCEPT 25.1 Elements move among geologic, atmospheric, oceanic, and biological pools at a global scale.

CONCEPT 25.2 Earth is warming because of anthropogenic emissions of greenhouse gases.

CONCEPT 25.3 Anthropogenic emissions of sulfur and nitrogen cause acid deposition, alter soil chemistry, and...
Coordination complexes: structure
Authors: Housecroft Catherine E.
Published: September 2023

This chapter introduces the ranges of coordination numbers observed for the heavier d-block metals. It cites selected examples of complexes. It analyses the coordination chemistry of yttrium as Y3+ ion and its complexes which exhibit a range of coordination numbers. It also talks about bulky amido ligands featured in complexes with low coordination numbers. The chapter refers to the coordination numbers for hafnium and zirconium which range from four to eight, such as the solid state MF4 that adopts a structure in which each metal centre is eight-coordinate. It points out that molecular stoichiometry in mononuclear compounds, such as halides, does not necessarily provide information about coordination number in the solid state.
Metals and solid compounds
Authors: McCleverty Jon
Published: September 2023

This chapter describes the elements encountered within the crust, wherein iron is fourth after oxygen, silicon, and aluminum that comprises about 6% of the total crustal composition. It discusses first-row transition elements, which includes titanium and manganese. It also talks about the majority of the elements that occur in minerals, such as oxides, hydrated oxides, and carbonates, including principal minerals and other sources of the elements. The chapter talks about vanadium that is found naturally in some living systems, particularly sea squirts, tunicates, and some mushrooms. It looks at trace amounts of chromium, which are responsible for the characteristic colours of ruby and emerald.
Non-Aqueous Solvents
Authors: Chipperfield John R.
Published: September 2023

Non-Aqueous Solvents covers the principles and uses of non-aqueous solvents. Solvents other than water are used in chemical analysis, chemical manufacturing, and in specialist syntheses. The book first discusses the general properties of solvents, and introduces the necessary concepts for making rational choices of solvents for different applications. There is a discussion of the various chemical interactions between solvents and the substances dissolved in them, and how solvents change the course of reactions. The chemistry of sixteen common solvents is examined, emphasising the advantages and disadvantages of each. The book concludes with an account of the chemistry of molten salts and discusses the use of low melting temperature compounds as synthetic media.
The clean surface
Authors: McCash Elaine M.
Published: September 2023

This chapter discusses the structure of the clean surface. Atoms in solids take up regular, ordered crystallographic structures. This results from minimizing their free energy, G. It should be noted that the minimum value of G obtained is the equilibrium value, which depends on precise pressure and temperature conditions. Thus, the crystallographic structure adopted may change with pressure or temperature. For metals such as copper, platinum, and nickel, the 'usual' adopted structure is face-centred cubic, in which each atom has twelve nearest neighbours. Meanwhile, for metals such as iron and molybdenum, a more open body-centred cubic structure is usually adopted, where each of the atoms has eight nearest neighbours. The chapter then looks at metallic bonding and surface energies. It also considers bonding in semiconductors, as well as surface structure and reconstruction.
Process Development
Authors: Atherton John H. , Carpenter Keith J.
Published: September 2023

Process Development starts off by looking at the scope of process development and strategies for process development, before moving onto pre-reaction equilibria. There are chapters on competing reactions in homogeneous media and mixing effects in pseudo-homogeneous systems. Next, the text covers equilibria in multiphase systems. It also explains dispersion and mass transfer in multiphase systems and mass-transfer and reaction in two-phase systems. Finally, the text looks at product isolation and workup and scale-up.
Competing reactions in homogeneous systems
Authors: Atherton John H. , Carpenter Keith J.
Published: September 2023

This chapter focuses on competing reactions in homogeneous systems. In process development, a good yield is often key to obtaining satisfactory material costs, purity, and robust operation. The essence of obtaining a good chemical yield is the understanding and control of those processes which compete with the desired reaction. This understanding is necessary to obtain a satisfactory laboratory process and, even more so, to scale-up the process for manufacture. The chapter then identifies the types of competing reaction. A pre-requisite for minimisation of side reactions is to know what they are. The commonest parameters used to manipulate absolute and relative reactivities are concentration, order of reactant addition, and temperature. The chapter also considers parallel/consecutive reactions; pH-rate and selectivity profiles; and methods for predicting reactivity.
Scale-up
Authors: Atherton John H. , Carpenter Keith J.
Published: September 2023

This chapter examines scale-up, which is the process of going from laboratory preparation to whatever scale of manufacture is required to satisfy the market demand. The science of scale-up is concerned with ensuring that the process performance in terms of yield, quality, and operability is not degraded when a process is transferred from laboratory to plant. It is not difficult in principle, but in practice can cause significant problems. The physical properties and characteristics of reaction systems are important in determining how they behave. The larger the dimensions and timescales involved in manufacturing processes mean that the parameters determining the performance of the laboratory process cannot all be reproduced at full scale. This means that, for each process which is to be scaled up, it is necessary to identify the physical factors which will change, and to consider how these will affect both the physical and chemical behaviour at full scale.
Step-growth polymers
Authors: Walton David J. , Lorimer J. Phillip
Published: September 2023

This chapter evaluates step-growth polymers. In the case of step-growth (condensation) polymers, the mechanism is simply an extension of the normal organic condensation reactions in which a small molecule is expelled as the link is built. This is a different situation to the chain polymerizations described in the previous chapter. It is assumed that most step polymerizations involve bimolecular reactions as key mechanistic processes. The chapter then looks at the kinetics of step polymerization. It also considers the commercial preparations of step-growth polymers. The industrial preparation of polyethylene terephthalate (PET) exploits the reversibility of esterification. A key feature in polymer technology is the manipulation of polymer properties by post-polymerization processing. PET behaviour is affected by its crystallinity.
Relativity, electronic spectroscopy, and magnetism
Authors: Kaltsoyannis Nikolas , Scott Peter
Published: September 2023

This chapter examines relativity, electronic spectroscopy, and magnetism. Relativity is most commonly associated with the world of the very large. It is less well known, however, that relativity also has a significant impact at the atomic level. In particular, the chemical consequences of relativity are very significant for heavy elements such as the actinides. These consequences may be divided into two main areas: the modification of atomic orbital energies and the effects of spin-orbiting coupling. The chapter then looks at electronic absorption spectroscopy, which is the study of photon/matter interactions, and has been extensively used to investigate f element compounds. It also considers the use of lanthanide ions in colour television sets, as well as neodymium lasers. Finally, the chapter studies the magnetic behaviour of Ln3+ and the magnetic properties of actinide compounds.
Crystal morphology
Authors: Davey Roger J. , Garside John
Published: September 2023

This chapter focuses on crystal morphology. The overall shape of a crystal—often called its habit, form, or morphology—is a vital parameter in determining the viability of both processes and products. It is usual to distinguish between ‘equilibrium’ and ‘growth’ morphologies. Morphology is determined by two factors: the symmetry of the internal crystal structure, which is manifest in the point group symmetry of the crystal form; and the relative growth rates of the faces bounding the crystal, which are related to the energetics of molecule or ion attachment to the crystal surfaces. The surface-specific nature of this attachment process means that crystal morphology can be dramatically influenced by external factors such as the level of supersaturation, temperature, the growth solvent, and solution purity.
Other ionic equilibria
Authors: de Levie Robert
Published: September 2023

This chapter assesses other ionic equilibria. Many ionic equilibria can be described through formalisms similar to that used for acid-base phenomena. The chapter briefly illustrates this, without going into detail. The successive complexation of metal ions by ligands has many feature in common with the stepwise protonation bases. However, there is one difference: the formation of metal-ligand complexes is typically described in terms of formation constants rather than ligand dissociation constants, where the latter would be the direct analogues of acid dissociation constants. The chapter then looks at the process of extraction, in which a given species is distributed over two contacting fluid phases. The extraction of metal ions often exploits their complexation equilibria, especially the much greater solubility in a non-polar organic phase of neutral over charged complexes. The chapter also considers solubility problems, precipitation titrations, and redox equilibria.
The measurement of pH, and its interpretation
Authors: de Levie Robert
Published: September 2023

This chapter explores some of the practical aspects of pH measurements. While measuring the pH is nowadays both easy and common practice, the interpretation of what is being measured is not quite so simple. The pH of a solution can be measured either electrometrically or spectrometrically. Spectrometry provides many different methods, the most common of which is visible or near-ultraviolet absorption spectrometry using indicator dyes, i.e. acid-base systems that exhibit a pH-dependent change in their spectra. Other methods include the Hammett acidity function and nuclear magnetic resonance (NMR) spectrometry. By far the most common method of measuring the pH is electrometrically, i.e. by measuring the potential difference between two electrodes immersed in the test solution. The chapter then looks at electrometric pH sensors, the electrometric pH measurement, and the pH meter.
Introduction
Authors: Brett Christopher M. A. , Brett Ana Maria Oliveira
Published: September 2023

This introductory chapter provides an overview of electroanalysis, which can be defined as the application of electrochemistry to solve real-life analytical problems. There are three types of electroanalytical measurement: conductimetric, potentiometric, and amperometric and voltammetric. In conductimetry, it is the concentration of charge which is obtained through the measurement of solution resistance—this is therefore not species selective. In potentiometry, the equilibrium potential of an indicator electrode is measured against a selected reference electrode using a high impedance voltmeter, i.e. effectively at zero current. Meanwhile, in amperometry, a fixed potential is applied to the electrode, which causes the species to be determined to react and a current to pass. More information and lower detection limits can usually be gained from the use of voltammetry. The chapter then outlines the general criteria for the design of electrochemical experiments, and offers a guide on how to choose the electroanalytical technique.
Applications
Authors: Brett Christopher M. A. , Brett Ana Maria Oliveira
Published: September 2023

This chapter offers a short overview of present developments and research in electroanalysis and its applications. It is not possible to describe all types of modern electroanalytical procedures. The chapter then looks at future developments in the area. Applications are particularly important in the areas of industrial, environmental, and clinical analyses. Present general challenges include the miniaturisation of electrochemical sensors, the reduction of their response time, their use on-line, and automation—which includes solving all associated problems such as periodic calibration, electrode fouling, and being sufficiently robust. To illustrate, the chapter provides examples from potentiometric sensors, electrode surface modification, microelectrodes, flow systems, hyphenated techniques, and bioelectroanalysis.
Orientation of electrophilic substitution reactions
Authors: Sainsbury Malcolm
Published: September 2023

This chapter evaluates the orientation of electrophilic substitution reactions. When an arene C6H5X is substituted by an electrophile R+, there are three principal sites for bonding: C-2 (ortho, o), C-3 (meta, m), and C-4 (para, p). Halogen atoms and most of the commonly encountered substituent groups, apart from alkyl units, are more electronegative than the sp
2 hybridized carbon atoms which constitute the benzene ring. As a result, a dipole is created and charge is withdrawn from the ring. The chapter then looks at resonance effects within sigma intermediaries. While resonance normally has the dominant role in determining the site adopted by the entering electrophile (the electromeric effect), the rate of the reaction is also influenced by the electron withdrawing power of the original substituent (the inductive effect). The chapter also considers ipso substitution, kinetic and thermodynamic control, and Birch reduction.
Electrode Dynamics
Authors: Fisher A. C.
Published: September 2023

Electrode Dynamics provides an introduction to the field of electrode dynamics. The word electrochemistry commonly instils fear in students. This text aims to distil this fear with a gentle introduction to the kinetics of electron transfer reactions, and explores the potential applications of electrochemistry methodology. The early chapters provide a general introduction to the factors which control the rate of an electrode reaction. The later chapters deal with a variety of electrochemical applications including the study of surface processes, reaction mechanisms, electrosynthesis and the combination of electrochemistry with complementary techniques such as spectroscopy.
Thermodynamic and kinetic considerations
Authors: Constable Edwin C.
Published: September 2023

This chapter focuses on the origins, quantification, and consequences of the macrocyclic effect. Complexes with multidentate ligands are more stable than those containing the same number of equivalent monodentate ligands. It is an obvious extension to ask if cyclic ligands give more stable complexes than corresponding open-chain ligands. This is indeed the case, and the phenomenon is described as the macrocyclic effect. The chapter then looks at the cryptate effect. In the same way that macrocyclic ligands give more stable complexes than open-chain ligands, polycyclic ligands form complexes that are more stable than the corresponding macrocycles. The chapter also considers kinetic aspects of macrocyclic coordination chemistry, as well as the formation and dissociation of macrocyclic complexes. Finally, it examines hole-size effects and metal ion selectivity.
Organometallics 1
Authors: Bochmann Manfred
Published: September 2023

Organometallics 1 outlines the main classes of transition metal organometallic complexes and introduces the reader to the chemistry of compounds with metal-carbon σ-bonds: metal carbonyls, metal alkyls, and metal alkylidenes and alkylidenes. The synthetic methods leading to each class of compounds are illustrated with pertinent examples, followed by the discussion of characteristic structures and reactivity patterns. The aim is to allow students a quick overview over this area of chemistry. Highlights and excursions stress general principles and relate the material to specific applications, such as catalytic processes.
A few basics
Authors: Bochmann Manfred
Published: September 2023

This chapter provides an overview of organometallic compounds, which are defined as substances containing direct metal–carbon bonds. The variety of the organic moiety in such compounds is practically infinite, ranging from alkyl substituents to alkenes, alkynes, carbonyls, and aromatic and heterocyclic compounds. Although some organometallic compounds have been known for a long time, it is only in the last four or five decades that organometallic chemistry has come into its own and experienced tremendous growth, both at a fundamental level where our insight into the nature of chemical bonds has been broadened by a variety of bonding situations without precedence elsewhere, and in its economic impact, such as catalysis. It is with the transition metals that the full diversity of organometallic chemistry becomes apparent. The chapter then explains the 18-electron rule, which provides a simple 'rule-of-thumb' basis for the discussion of structure and bonding.
Fundamental principles
Authors: Green N. J. B.
Published: September 2023

This chapter discusses some of the fundamental principles in quantum mechanics. Towards the end of the nineteenth century, it had been thought that all the fundamental laws of nature were well-understood. However, the next 20 years saw the development of both quantum mechanics and relativity. The chapter then looks at the representation of a particle by a wavefunction. It also considers operators, observables, eigenfunctions, and eigenvalues, as well as commutation and uncertainty. Since it is not possible for a wavefunction to have characteristic values of two observables with non-commuting operators, it is not possible to specify exact simultaneous values for these observables. It should be noted that the uncertainty principle is rather deeper than the usual physical explanation might imply, it is actually inherent in the description of matter in terms of wavefunctions. Finally, the chapter explains expansion in eigenfunctions; the variational principle; and transition probabilities.
Separations
Authors: Green N. J. B.
Published: September 2023

This chapter examines the separation of variables in quantum mechanics. Although many mathematical methods are available for one-dimensional eigenvalue problems, multi-dimensional partial differential equations are much more difficult to solve, often requiring computational methods. The first step is therefore to search for some means of reducing the problem to a collection of one-dimensional equations, which can be solved separately. The procedure involved is called the separation of variables. The chapter first outlines the method of separation of variables before considering how it is applied to problems in chemistry. It looks at spherical symmetry; the Born–Oppenheimer separation; spin; orbital approximation; the diatomic molecule; and the vibrations of a polyatomic molecule.
Exact solutions
Authors: Green N. J. B.
Published: September 2023

This chapter evaluates some of the simplified Schrödinger equations obtained in the previous chapter, and presents explicit solutions for the energy levels and the corresponding wavefunctions. It begins by looking at the free particle and the particle in a box. The particle in a box is the simplest example of a confined particle, and enables us to understand the origin of many features of such systems, such as the appearance of discrete energy levels. It is a general feature of particles confined by a potential to some region of space that solutions to the Schrödinger equation can only be found at certain discrete energies. The chapter then considers the harmonic oscillator; angular momentum; rotations of a polyatomic molecule; and the hydrogen atom.
Symmetries—group theory
Authors: Green N. J. B.
Published: September 2023

This chapter focuses on symmetries and group theory. Each vibration of a molecule has a particular symmetry, and only certain combinations of the coordinates have the correct symmetries. Use of these symmetry-adapted combinations brings the matrix into a form in which it is already partly diagonalized, making the remaining problem much simpler. In a similar way, the simplest approximations to molecular orbitals are obtained by a linear combination of atomic orbitals. The problem is to find the suitable weightings. However, each molecular orbital has a symmetry, and if we construct symmetry-adapted linear combinations, once again the size of the problem can be much reduced. The chapter then looks at symmetry operations; point groups; and bases and representations. It also considers the reduction of representation; energy levels, degeneracies, and irreps; projection operators; the descent of symmetry; vanishing integrals; and direct products.
Molecular orbitals
Authors: Green N. J. B.
Published: September 2023

This chapter studies the electronic wavefunction, which determines the distribution of electrons in the molecule, and therefore the bonding. Chemists describe bonding in terms of atomic and molecular orbitals, and the chapter shows how group theory can be used to classify the symmetries of orbitals and to find suitable combinations of atomic orbitals for the construction of a molecular orbital. It begins by considering the case of atoms before proceeding to the more complex problem of molecules. In the orbital approximation, the electronic wavefunction of an atom is constructed as a product of one-electron wavefunctions, or orbitals. Each orbital obeys a Schrödinger equation. The chapter then looks at the linear combination of atomic orbitals (LCAO) method; π bonding; and orbital symmetry and chemical reactivity.
Biocoordination Chemistry
Authors: Fenton David E.
Published: September 2023

Biocoordination Chemistry introduces this field. The role of the transition metals in biological systems is of great interest to chemists: the chemical properties of these metals often define the biological function of the proteins and systems these metals are found in. This book introduces a number of topics: the transport and storage of metals, their functions in dioxygen interactions, electron-transfer, and enzyme activity; the therapeutic uses of coordination compounds; and the role that small-molecule models can play in advancing our knowledge of the structure and function of transition metals contained in metallobiosites.
‘Life is inorganic too’
Authors: Fenton David E.
Published: September 2023

This chapter begins by discussing the thirteen metals which are essential for plants and animals. Four of these—sodium, potassium, magnesium, and calcium—are present in large quantities and are known as the bulk metals. The remaining nine, which are present in small quantities, are the d-block elements vanadium, chromium, molybdenum, manganese, iron, cobalt, nickel, copper, and zinc. These are known as the trace metals. It is this latter group that we are concerned with in biocoordination chemistry. The chapter then looks at nonmetallic elements, metals in biological systems, trace metals, and the ultratrace metals. It also considers the roles of metal ions in biological systems, as well as metallobiosite structures and the entatic state.
Quantization and molecular energy levels
Authors: Brown John M.
Published: September 2023

This chapter discusses the physical properties of atoms and molecules, which are quantized. This means that they can only take certain discrete values rather than a full range of continuously varying values. The chapter examines the quantized energy levels of a molecule. These are called stationary states, which describe an energy that is independent of time. The chapter also outlines the procedure for constructing a quantum mechanical Hamiltonian, which includes writing down the complete and classical expression for the energy of the system. The chapter reviews the general approach to the determination of energy levels of a physical system. This involves two stages: First, the appropriate Hamiltonian is defined and, in a second step, the eigenfunctions and eigenvalues of the Hamiltonian are determined. The chapter also discusses the Schrödinger equation, which can only be solved for one-body systems.
Vibrational spectroscopy
Authors: Brown John M.
Published: September 2023

This chapter defines vibrational motion, which is a periodic, concerted displacement of the nuclei in a molecule that leaves the centre of mass unaltered in laboratory space. It explains that the appropriate linear combination of the displacements of a nucleus from its equilibrium position is called the vibrational coordinate, which is used to describe a particular vibrational motion. It also mentions the polyatomic molecule. This has several distinct vibrational modes, while the diatomic molecule only has one. The chapter reviews two distinct contributions to energy: the kinetic part that arises from the motion of the nuclei and the potential part that comes from the compression or expansion of the bond from its equilibrium value. It highlights the form of the potential energy curve. This shows that molecular energy increases rapidly as the charged particles in the molecule experience strong repulsive forces.
Selectivity I: Chemoselectivity and protecting groups
Authors: Willis Christine L. , Wills Martin
Published: September 2023

This chapter evaluates chemoselectivity and protecting groups. In a chemoselective reaction, one functional group within the molecule reacts, leaving further potentially reactive functionality unaffected. Many of the principal transformations involved in functional group interconversions (FGIs) were introduced in the third chapter of this text. The reactions may involve addition, substitution, elimination, reduction, and oxidation. There are now a plethora of mild and selective reagents available to effect specific transformations. As a general rule, when there are two functional groups of unequal reactivity within a molecule, the more reactive can be made to react alone. However, it may not be possible to react the less reactive functional group selectively.
Alkene synthesis (Peterson olefination)
Authors: Thomas Susan E.
Published: September 2023

This chapter highlights the key compounds in the application of organosicilicon chemistry to the synthesis of alkenes: β-hydroxysilanes. It describes the three methods of generating them starting with the addition of α-metallated silanes to carbonyl compounds. α-Metallated silanes may be generated in several ways including addition of organometallic nucleophiles to vinylsilanes, deprotonation of α to silicon, and metal-halogen exchange. The chapter then investigates another method of generating β-hydroxysilanes: the addition of dialkylcuprates to α, β-epoxysilanes. α, β-epoxysilanes are readily synthesized by epoxidation of vinyl silanes. They react with organocuprate reagents in a regiospecific manner to give β-hydroxysilanes. Finally, the chapter elaborates on the last method of generating β-hydroxysilanes: the addition of hydride sources or organometallic reagents to β-ketosilanes. It also considers the conversion of β-hydroxysilanes into alkenes and some examples of silicon-based alkene synthesis.
Isotope effects upon organic chemical reactions
Authors: Maskill Howard
Published: September 2023

This chapter assesses isotope effects upon organic chemical reactions. In particular, it looks at the effect of isotopic substitution upon reactants in a single reaction. On the one hand, the replacement of one isotope by another (e.g. protium and deuterium) does not alter the chemical identity of the element and, consequently, the natures of the reactions of compounds remain unchanged. In other words, the potential energy hypersurface of the chemical system is independent of the pattern of isotopic substitution. On the other hand, isotopic substitution does alter the masses of groups within molecules and hence vibrational frequencies. On the basis that an equilibrium is a balance between forward and reverse kinetic processes, we may also expect that isotopic substitution will alter the value of an equilibrium constant, but not the nature of the equilibrium.
Back donation to Born-Haber cycle
Authors: Mingos D.M.P.
Published: September 2023

This chapter begins by examining back donation, base metal, bond energies, and bond order. The bond dissociation energy for a diatomic covalent molecule is the change in internal energy, where the parent molecule and product atoms are in their ground electronic states. For polyatomic molecules, there is more than one bond dissociation energy and one must be careful to specify exactly the dissociation process being referred to. Meanwhile, bond order is a prediction from theoretical considerations of the relative strength of a bond. The chapter then explains the Born–Haber cycle, a cycle of reactions based on the first law of thermodynamics, or Hess’s law, which is used to calculate the lattice energy of an ionic compound.
Canonical form to crystal structures
Authors: Mingos D.M.P.
Published: September 2023

This chapter begins by evaluating the canonical form and defining a catalyst and catenation. The canonical form is a theoretical resonance form of a molecule used in valence bond theory. A catalyst is a substance which increases the rate of a chemical reaction without being consumed in the reaction. At the molecular level, the catalyst lowers the activation energy by participating in a cyclical series of reactions, each of which has a low activation energy. The catalyst is regenerated at the end of each cycle of reactions. Meanwhile, catenation is the ability of an element to form a wide range of molecular compounds containing element–element bonds. The chapter then looks at chalcogens, chelate, clathrate, coinage metals, co-ordination compound and geometry, core electrons, covalent bond, cryptand, crystal field theory, and crystal structures.
Dative bond to dipole moment
Authors: Mingos D.M.P.
Published: September 2023

This chapter focuses on the dative bond and the dipole moment. A dative or co-ordinate bond is a covalent bond which originates from the donation of an electron-pair from one atom (or group of atoms) to an empty orbital on a second atom. Although the origin of the electron-pair in a co-ordinate bond is usually a lone pair on the donating atom, it can also be an electron-pair residing in a bonding σ- or π-orbital. Molecules act as electric dipoles if the charge distribution in them corresponds to a separation of regions of partial positive and negative charges. This occurs when the vector sum of the bond and lone pair dipole moments have a non-zero resultant.
Halogens to hypervalent
Authors: Mingos D.M.P.
Published: September 2023

This chapter describes halogens, which are the group 17 elements of the Periodic Table, before explaining Hess’s law. Hess’s law derives from the first law of thermodynamics, which states that energy can neither be created nor destroyed, although it may be converted from one form to another. According to Hess’s law, the overall reaction enthalpy is the sum of the reaction enthalpies of the individual reactions into which a reaction may be theoretically divided. The chapter then looks at Hund’s rules, hybridization, and hydration enthalpy. The hydration enthalpy is the standard enthalpy change for the formation of a hydrated ion from its gaseous state. The chapter also considers hydrogen bonds and hypervalent molecules.
Valence bond to VSEPR
Authors: Mingos D.M.P.
Published: September 2023

This chapter begins by explaining the valence bond, which is a quantum mechanical expression of the Lewis concept of the bond, whereby it is assumed that structures with all the electrons paired in all possible ways dominate the structure wavefunction of the molecule. The final wavefunction is a superposition of all possible perfectly paired canonical structures with those of lowest energy making the main contribution. This superposition is described as resonance. The chapter then explores the valence shell electron-pair repulsion (VSEPR). VSEPR is a semi-classical theory which accounts qualitatively for the shapes of most main group molecules. Electron pairs are an important feature of the Lewis description of chemical bonds and VSEPR gives a geometric dimension to the theory by proposing that the most favourable molecular shape is that which minimizes the repulsion between sigma-bonding electron-pairs around specific atoms.
Metal-Metal Bonded Carbonyl Dimers and Clusters
Authors: Housecraft Catherine E.
Published: September 2023

Metal-Metal Bonded Carbonyl Dimers and Clusters provides an introduction to this topic. Metal-metal bonded dimers and clusters in which the metals are in low oxidation states and associated with pi-acceptor ligands represent a large group of inorganic compounds. Research interest in the area has been generated in part by potential uses of some compounds as catalysts and, in respect of the clusters, for their possible use as molecular models for surfaces. Bonding in many of the compounds is not readily rationalized in terms of localized bonding schemes.
Chemical Change
Authors: Wayne Carol E. , Wayne Richard P.
Published: September 2023

This chapter discusses the processes involving excited species which lead to chemical change, i.e. reactions in which the reactants and products differ in chemical identity rather than in state of excitation. Chemical change can come about as a result of photodissociation of the absorbing molecule into fragments, direct reaction of the excited species, or spontaneous isomerization of the excited species. Photodissociation is the most obvious type of chemical change. Several mechanisms are recognized for dissociation processes; the three major routes are optical dissociation, predissociation, and induced predissociation. The chapter then looks at photosensitized reactions; intramolecular and intermolecular abstraction reactions; and photoaddition and photocyclization reactions. It also considers multiphoton photochemistry and state-to-state photochemistry.
The electronic basis of stereoelectronic effects
Authors: Kirby A.J
Published: September 2023

This chapter discusses the electronic basis of stereoelectronic effects. It introduces some of the ideas on which current thinking about electrons in molecules are based. The ideas presented here come originally from modern theoretical chemistry, and have developed over the last twenty years into our most powerful and creative way of thinking about reactivity. The chapter then looks at orbital-orbital interactions. If the interaction is strong enough — that is to say, if the energy of the lower molecular orbital is low enough relative to the two starting atomic orbitals — electrons that were originally in the atomic orbitals will prefer to occupy the new bonding molecular orbital. The result will be a covalent bond. The chapter also considers the interactions between molecules; hard and soft acids and bases; geometrical restrictions on orbital overlap; and the status of lone pair electrons.
Additions and eliminations
Authors: Kirby A.J
Published: September 2023

This chapter assesses a large number of important reactions, which have in common the interconversion of sp2 and sp3-hybridized centres. In some cases, the overall reaction is substitution rather than addition or elimination. The more closely one looks at the orbital interactions involved, the clearer become the underlying similarities between different mechanisms. Stereoelectronic effects on some E2 reactions show marked similarities to stereoelectronic effects on SN1 reactions. Addition reactions going by ionic mechanisms involve the addition of both a nucleophile and an electrophile, almost always in separate steps. The usual classification into nucleophilic and electrophilic addition is based on the main HOMO/LUMO interaction in the rate determining step. For additions to ordinary alkenes, this involves the interaction of the π-bonding orbital with the LUMO of the electrophile.
Radical reactions
Authors: Kirby A.J
Published: September 2023

This chapter explores radical reactions. Stereoelectronic effects on radical reaction arise from geometrical preferences for optimal orbital-orbital interactions, in the same way as the effects on ionic reactions discussed in the previous chapters. The geometries of the relevant orbital-orbital interactions are the same as in the corresponding ionic reactions because the orbitals involved are the same. What is different is that the interacting orbitals contain an odd number of electrons. Meanwhile, stereoelectronic effects on reactivity are generally simpler than for ionic reactions because the reactions are simpler. The chapter then looks at the stability of radicals and reactivity, before examining intramolecular reactions and reactions involving diradicals.
Thermal rate coefficients
Authors: Brouard M.
Published: September 2023

This chapter assesses thermal rate coefficients. It begins by looking at canonical transition state theory (CTST), focusing on the derivation and application of transition state theory to bimolecular reactions. The discrepancy between CTST and the experimental rate coefficients can be ascribed to the neglect of tunnelling in the CTST calculation. However, classical mechanics works rather well, suggesting that the absence of a tunnelling contribution to the classical rate coefficient is offset by the absence of zero point vibrational energy in the barrier region, which lowers the effective barrier height compared with the quantum mechanical one. The chapter then examines thermally activated unimolecular reactions. In a thermally activated unimolecular reaction, the molecule acquires the energy necessary to react by energy-transferring collisions, and like the elementary reaction step, the rate coefficients of these activating and deactivating collisions also depend on the energy of the energized molecule.