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Advanced Chemistry 1 ADVANCED CHEMISTRY 1 Philip Matthews B&& CAMBRIDGE UNIVERSITY PRESS Contents Acknowledgements pagex 5 Radioactive decay 28 How to use this book xi 5.1 Detection of radiation 28 5.2 Half-lives 29 5.3 The radioactive decay law 31 5.4 Decay schemes 31 PHYSICAL CHEMISTRY 6 Nuclear energy 34 1 Elements, atoms and electrons: basic 6.1 Discovery of nuclear energy 34 ideas 3 6.2 Fission reactions 34 1.1 Dalton's atomic theory 3 6.3 Nuclear power 35 1.2 Evidence for atoms 5 6.4 Fusion reactions 37 1.3 Cathode rays 6 6.5 Nuclear weapons 38 1.4 Millikan's experiment 6 1.5 Electric Charge is quantised 7 7 Applications of radioactivity 41 7.1 Industrial uses of radioactivity 41 2 Energy levels 9 7.2 Medical uses of radioactivity 42 2.1 Energy changes 9 7.3 Radiocarbon dating 42 2.2 Energy levels 9 7.4 Chemical applications 43 2.3 Max Planck and energy levels 11 2.4 Light energy 11 8 Bohr's model of the atom 46 8.1 Energy levels of the hydrogen atom 46 3 Atoms and the nucleus 13 8.2 How to calculate the ionisation energy of 3.1 A plum pudding 13 hydrogen 47 3.2 How the nucleus was discovered 13 8.3 What are Orbitals? 48 3.3 The discovery of protons 14 8.4 What are stationary states? 48 3.4 Moseley and atomic number 15 8.5 Ground and excited states 49 3.5 Discovery of neutrons 15 3.6 A comparison of electrons, protons and 9 The hydrogen atom spectrum 51 neutrons 16 9.1 Balmer's formula for the hydrogen atom 51 3.7 Isotopes 17 9.2 Bohr's explanation 51 3.8 Atomic mass units 17 9.3 Other lines in the hydrogen spectrum 51 3.9 Relative atomic and molecular masses 18 3.10 Einstein's equation 18 10 Waves and particles 54 3.11 Binding energy 20 10.1 Experimental evidence about the nature 3.12 Mass defect and mass excess 21 of light 54 10.2 What is wave—particle duality? 56 4 Discovery of radioactivity 23 10.3 de Broglie's equation 56 4.1 The discovery of radioactivity 23 4.2 New elements 24 11 Schrödinger's theory of the atom 58 4.3 Some properties of radiation 24 11.1 Schrödinger's theory of the hydrogen 4.4 Units of radioactivity 25 atom 58 4.5 Nuclear reactions 25 11.2 What do the quantum numbers teil us? 59 4.6 Artificially prepared elements 26 11.3 Different types of orbital 59 4.7 A sad ending 27 11.4 Wavefunctions and what they mean 60 11.5 The shapes of orbitals 61 18.2 Ionic substances have some covalent 11.6 The spin quantum number 63 character 101 18.3 Other evidence that a substance contains 12 The aufbau method and electron ions 102 structures 66 18.4 Which elements make ionic Compounds? 103 12.1 What is the aufbau method? 66 18.5 Why do ionic Compounds exist? 103 12.2 More about orbital energies 66 18.6 Ionic Compounds and electron structures 104 12.3 Filling orbitals - the importance of energy 67 12.4 The Pauli exclusion principle 67 19 Polar molecules and polar bonds 107 12.5 Hund's rule 68 19.1 What is a polar molecule? 107 12.6 Background to Hund's rule 68 19.2 Polar bonds and electronegativities 107 12.7 The aufbau method in action 68 19.3 Polar molecules and dipole moments 108 19.4 Polarisability 111 13 Electron structures, ionisation energies and shielding 71 20 Intermolecular forces 113 13.1 What is shielding? 71 20.1 Where are intermolecular forces found? 113 13.2 Ionisation energies down a Group 71 20.2 What causes intermolecular forces? 113 13.3 Ionisation energies across a Period 72 20.3 Dispersion forces and polarisability 114 13.4 How ionisation energies are linked to 20.4 Intermolecular forces are also produced Groups in the Periodic Table 73 by permanent dipoles 114 20.5 Some words of warning 114 14 Bonding in molecules: valence bond theory 77 21 Hydrogen bonding 117 14.1 Valence bond theory 77 21.1 What is hydrogen bonding? 117 14.2 Dot-and-cross diagrams for diatomic 21.2 Evidence for hydrogen bonding 117 molecules 78 21.3 Intermolecular and intramolecular 14.3 Dot-and-cross diagrams for triatomic and hydrogen bonding 119 quadratomic molecules 78 21.4 Hydrogen bonding in biochemistry 120 14.4 Dot-and-cross diagrams for hydrocarbons 79 21.5 Hydrogen bonding in solids 120 14.5 Showing bonds by lines 79 14.6 Bonding in oxoanions 80 22 Metallic bonding 122 14.7 Resonance structures 80 22.1 How can you recognise a metal? 122 22.2 What is the band structure of metals? 122 15 Coordinate bonding 84 22.3 Why do metals conduct electricity? 123 15.1 What is coordinate bonding? 84 22.4 Semiconductors 123 22.5 Why do metals conduct heat? 126 16 Molecular orbital theory 87 22.6 Metal atoms exist in a sea of electrons 126 16.1 Wavefunctions can be positive or negative 87 23 The three states of matter 128 16.2 How wavefunctions can be combined 87 23.1 The three states of matter 128 16.3 Bonding and antibonding orbitals using s 23.2 How do we know that gases are disorderly? 129 orbitals 87 23.3 Differences in properties of solids, liquids 16.4 Bonding and antibonding orbitals using p and gases 129 orbitals 88 23.4 The potential energy curve for two 16.5 Energies of bonding and antibonding neighbouring molecules 130 orbitals 89 23.5 Some remarkable substances 130 16.6 Molecular orbitals for homopolar diatomic molecules 90 24 Three types of spectroscopy 136 16.7 Molecular orbitals for heteropolar 24.1 Emission and absorption spectra 136 diatomic molecules 91 24.2 Electronic spectroscopy 136 16.8 Molecular orbitals for hydrocarbons 92 24.3 Vibrational spectroscopy 136 24.4 Rotational spectroscopy 136 17 Shapes of molecules 95 24.5 Translations 138 17.1 Molecular modeis 95 24.6 Electromagnetic waves 138 17.2 Electron repulsion theory 95 24.7 The electric field and electrons 139 17.3 The isoelectronic rule 96 24.8 The magnetic field and electrons 139 17.4 Hybridisation 97 24.9 Selection rules 140 18 Ionic bonding 101 25 Visible spectroscopy 142 18.1 Covalent substances have some ionic 25.1 Why does copper(n) sulphate Solution character 101 lookblue? 142 IV Contents 25.2 The visible spectrum of copper(n) 32 Unit cells 179 sulphate Solution 142 32.1 The seven crystal Systems 179 25.3 How does a visible light spectrometer 32.2 The fourteen Bravais lattices 179 work? 143 32.3 What are unit cells? 179 25.4 What happens to the photons absorbed 32.4 Radius ratio rules 184 by copper(n) sulphate Solution? 144 32.5 The number of atoms or ions in a unit 25.5 Why vibrations are important in visible cell 185 spectra 144 33 Sizes of atoms, ions and molecules 188 26 Ultraviolet spectroscopy 146 33.1 How can we estimate the size of an 26.1 The ultra violet spectrum of alkenes 146 atom? 188 26.2 The ultraviolet spectrum of arenes 147 33.2 Metallic and covalent radii 188 26.3 The ultraviolet spectrum of aldehydes 33.3 Van der Waals radii 189 and ketones 147 33.4 Ionic radii 190 33.5 Bondlengths 191 27 Vibrational spectroscopy 149 27.1 Why is vibrational spectroscopy useful? 149 34 Real and ideal gases 193 27.2 What are group frequencies? 151 34.1 The gas laws 193 27.3 Making sense of vibrational spectra 151 34.2 Real gases and the van der Waals 27.4 Vibrational spectra can teil us about the equation 195 strengths of bonds 155 34.3 How good is the van der Waals equation? 196 35 Kinetic theory of gases 200 28 Nuclear magnetic resonance 157 What is the kinetic theory of gases? 200 28.1 The importance of nuclear spin 157 35.1 The pressure of an ideal gas 200 28.2 The patterns in an n.m.r. spectrum 158 35.2 The connection between energy and 28.3 Why do protons appear in different 35.3 temperature 201 places in the spectrum? 158 The spread of energies in a gas 202 28.4 N.m.r. spectra can teil us how many 35.4 protons are present 158 35.5 Kinetic theory and Avogadro's theory 203 28.5 Not only hydrogen atoms can show up in 36 n.m.r. 159 Chemistry and gases 205 36.1 Gay-Lussac's law of combining volumes 205 36.2 Avogadro's theory 205 29 Mass spectrometry 161 36.3 Dalton's law of partial pressures 206 29.1 What are mass spectrometers? 161 36.4 Graham's law of diffusion 206 29.2 The design of a mass spectrometer 161 29.3 The whole number rule and Standards of 37 The mole 209 mass 162 37.1 What is the mole? 209 29.4 Mass spectra and isotopes 164 37.2 How to work with moles of Compounds 210 29.5 Calculating relative atomic masses from 37.3 Moles and equations 210 mass spectra 164 37.4 Moles and balancing equations 211 29.6 What are fragmentation patterns? 164 37.5 The empirical formula and molecular 29.7 The effect of isotopes in a molecule's mass formula of a Compound 212 spectrum 165 37.6 Percentage compositions 213 30 X-ray diffraction 168 38 Molar masses of gases and liquids 216 30.1 What causes X-ray diffraction? 168 38.1 Measuring the molar mass of a gas 216 30.2 More about diffraction 168 38.2 Measuring the molar mass of a soluble 30.3 Bragg's equation 169 gas 217 30.4 Different types of X-ray diffraction 38.3 Measuring the molar mass of a volatile experiment 169 liquid 218 30.5 Explanation of powder photographs 170 30.6 The arrangement of planes in crystals 171 39 Moles and titrations 221 30.7 The arrangements of individual atoms 172 39.1 Standard Solutions 221 39.2 The concentration of a Solution 223 31 Crystallography 174 39.3 Concentration and molarity 224 31.1 What is crystallography? 174 39.4 How to do calculations involving 31.2 The dosest packing of atoms 174 concentrations 224 31.3 Structures that are not close-packed 176 31.4 C oordination numbers 176 40 Four types of titration 227 31.5 Metal crystals 176 40.1 Acid-base titrations 227 Contents v 40.2 Redox titrations 227 49.2 The Boltzmann distribution 281 40.3 Titrations involving iodine 229 49.3 More about energy levels 281 40.4 Silver nitrate titrations 230 49.4 Entropy changes and mixing
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