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INORGANIC CHEMISTRY

INORGANIC CHEMISTRY. Teachers : Prof. Zhang Wei-guang ( 章伟光） Tel: 13416250262(HP), E-mail: wgzhang@scnu.edu.cn Dr. Fan Jun （范军） Tel: 85210267(H), 85210875(o); E-mail: fanj@scnu.edu.cn. Sept. 2005 For Science Class 2. INORGANIC CHEMISTRY. Contents. Contents.

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INORGANIC CHEMISTRY

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  1. INORGANIC CHEMISTRY Teachers: Prof. Zhang Wei-guang (章伟光） Tel: 13416250262(HP), E-mail: wgzhang@scnu.edu.cn Dr. Fan Jun（范军） Tel: 85210267(H), 85210875(o); E-mail: fanj@scnu.edu.cn Sept. 2005 For Science Class 2

  2. INORGANIC CHEMISTRY Contents Contents Introduction Section A Atomic structure Section B Introduction to inorganic substance Section C Structure and bonding in molecules Section D Structure and bonding in solids

  3. INORGANIC CHEMISTRY Contents Section E Chemistry in solution Section F Chemistry in nonmetals Section G Non-transition metals Section H Chemistry of transition metals Section I Lanthanides and actinides Section J Environmental, biological and industrial aspects

  4. INORGANIC CHEMISTRY Introduction Introduction 1. Emergence and Development of Chemistry Pride of Chemist Four Inventions in ancient China and Alchemy in ancient Greece Set up theoretic system of modern chemistry and industry Nature phenomenon: Burning, Volcano breaking out, and Lightning, etc. High technology production in modern civilization

  5. INORGANIC CHEMISTRY Introduction 2. Brach of Chemistry Inorganic Chemistry Coordinary Chemistry Polymer Chemistry Organic Chemistry CHEMISTRY Organometallic Chemistry Analytical Chemistry Electro-Chemistry Physical Chemistry Structural Chemistry …… etc. Biochemistry Geochemistry Spacechemistry Material Chemistry Nano-Chemistry

  6. INORGANIC CHEMISTRY Introduction 3. Ways of Learning Chemistry Study hard Learn cleverly Do it yourself

  7. INORGANIC CHEMISTRY Introduction 4. Some basic conception in Chemistry Nucleus reaction Protons + Neutrons = Nucleus Breaking Atoms Get or Lost Molecules Forming Electrons Chemical reaction

  8. INORGANIC CHEMISTRY Introduction Atom Nucleus Electrons + Removal (addition) of electrons Removal (addition) of Protons or Neutrons Isotopes, New Element Ions, Free radical Isotopes are atoms with the same atomic number but different numbers of the neutrons for one element, so their mass numbers will be different. They have the same amount of protons. Potential application: NMR, dating and origin of rocks, the studies for the reaction mechanism, etc

  9. INORGANIC CHEMISTRY Introduction Gas Species discussed in this course Liquid, Solution Solid n-----mol Molar mass-----gmol-1 Molar volume---- m3mol-1lmol-1, dm3mol-1 Pressure, P-----Pa, KPa, atm Temperature, T-----K, ℃ Energy----- J, or kJ, cal, kcal SI units:

  10. INORGANIC CHEMISTRY Gas 1. Ideal-gas Law No intermolecular interaction Ideal gas The volume of the molecules in gas would be considered as zero. GAS Real gas This content would be introduced in Physics and Physical Chemistry. (1) Ideal-gas equation For the mono-component ideal-gas P——pressure (Pa); V ——volume (m3); n —— moles (mol); T ——temperature (K) T= t + 273.15; d —— density (gmol-1) P V = n R T (i) If SI units would be used, R = 8.314 Jmol-1K-1; (ii) P—KPa, V—dm3, T—K, n—mol, R = 8.314 Jmol-1K-1; (ii) P—atm, V—l, T—K, n—mol, R = 0.08206 atm lmol-1 K-1

  11. INORGANIC CHEMISTRY Introduction • For example: • 现在一般能得到的最高真空是10-12托(1托＝1 mmHg)。求27℃下体积为1ml的真空体系中的气体分子数。 • P V = n R T n = PV/(RT) = 5×10-20 mol • N＝ n×6.023×1023 ＝ 3×104 个 • 空气的N2和O2的体积比例分别为79％与21％，计算空气在25℃和100KPa下空气的密度是多少？(gdm-3) • M ＝28×79％＋32×21％＝ 28.8 • d ＝ 1.16 gdm-3

  12. INORGANIC CHEMISTRY Introduction (2) Law of partial pressure For the Poly-component ideal-gas If the chemical reaction don’t take place among the component, the total moles would keep constant after mixed them. If V=0 and  T=0, partial pressure of one kind of component Mole fraction

  13. INORGANIC CHEMISTRY Gas • For example: • 将730mmHg 压力的氮气60ml，300mmHg 压力的氧气200 ml及420mmHg压力的氢气80ml 压入250ml 的真空瓶中，求混合后的气体分压力和混合的总压力。 PN2= 175mmHg, PO2=240mmHg, PH2=134mmHg， PT = 549mmHg (2)某容器中含有NH3、O2、N2等气体的混合物。取样分析后，其中n(NH3)=0.320mol，n(O2)=0.180mol，n(N2)=0.700mol。混合气体的总压p=133.0kPa。试计算各组分气体的分压。 n= n(NH3)+n(O2)+n(N2)

  14. INORGANIC CHEMISTRY gas (3) Diffusion Law of gas u－－the diffusion rate of the gas molecules d－－the density of the gas M－－the mole mass of the gas (4) Real gas Homework: 1, 3, 7

  15. INORGANIC CHEMISTRY Section A1 Section A Atomic structure A1 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Nucleus: positive charge Electron: negative charge Electrostatic attractive force: Electrons are attracted to Nucleus. Electrostatic repulsion force: among the protons. From planetary model to quantum theory Electron and Nuclei

  16. INORGANIC CHEMISTRY Section A1 Nuclear structure Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. Electrostatic attractive force: Electrons are attracted to Nucleus The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Electrostatic repulsion force: among the protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Magic numbers: 2 8 20 28 50 82 126 16(8+8)O 208(82+126)Pb

  17. INORGANIC CHEMISTRY Section A1 Isotopes Isotopes are atoms with the same atomic number but different numbers of neutrons. Many elements consist naturally of mixtures of isotopes, with very similar chemical properties. Only one stable isotopes: 9Be, 19F, 23Na, 27Al, 31P, Sc, Mn, etc. total numbers: 20. Several stable isotopes: 1H, Deuterium: 2H, 3H; 12C, 13C, 14C; etc. Tin (Sn): no fewer than 10. Relative atomic mass (RAM) is equal to molar mass of element RAM of an element: fi: the abundance of the isotopes in the nature; Mri: the relative atomic number of the isotopes

  18. INORGANIC CHEMISTRY Section A1 Application: (1) NMR: 2H, 13C, nuclear magnetic resonance (2) Unstable radioactive: medical diagnostics (3) 14C: judge years; (4) investigate the detailed mechanism of chemical reactions Nuclides (核素): Isotopes (同位素): Element (元素): Atom (原子): isotone (同中素): Isobar (同量异位素):

  19. INORGANIC CHEMISTRY Section A1 Radioactivity: Radioactive decay: is a process whereby unstable nuclei change into more stable ones by emitting high-energy particles of different kinds. All elements with Z > 83 are radioactive. The process involved are as follows: (a)  decay: 4He (b)  decay: electron (c)  decay: high-energy electromagnetic radiation. It often accompanies  and  decay. Half-life:

  20. INORGANIC CHEMISTRY Section A2 A2 ATOMIC ORBITALS Wavefunctions The quantum theory is necessary to describe electrons. It predicts discrete allowed energy levels and wavefunction, which give probability distributions for electrons. Wave functions for elections in atoms are called atomic orbitals. Quantum mechanics Quantized energy Probability distributions Schrödinger’s wave equation Atomic orbitals

  21. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Section A2 Atomic orbitals are labeled by three quantum numbers n,l and m. Orbitals are called s,p,d or f according to the value of 1; there are respectively one, three,five and seven different possible m values for these orbitals. Principal Quantum numbers n=1, 2, 3….. Angular momentum (or azimuthal) Quantum numbers l=0, 1, 2, …, (n-1) Magnetic Quantum numbers m=0, ±1, ±2, …, ±(n-1) Spin Quantum numbers ms=+1/2, -1/2 Quantum numbers and nomenclature A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  22. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Section A2 s orbitals are spherical. p orbitals have two directional lobes, which can point in three possible directions. d and f oritals have coorespondingly greater numbers of directional lobes. Radial wavefunction Angular wavefunction Polar diagrams Boundary surface Nodal plane Angular functions: ‘shapes’ A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  23. INORGANIC CHEMISTRY Section A2

  24. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Section A2 The radial distribution function shows how far from the nucleus an election is likely to be found. The major features depend on n but there is some dependence on l. Radial probability distributions Radial distributions A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  25. INORGANIC CHEMISTRY Section A2

  26. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Section A2 The allowed energies in hydrogen depend on n only. They can be compared with experimental line spectra and the ionization energy. En= -R/n2 Rydberg constant: R=13.595 eV per atom When n=∞, E∞=0 which is the ionization limit Ionization energy: E∞-E1=R Degenerate: Orbitals with the same n but different values of l and m have the same energy. Energies in hydrogen A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  27. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A2 Increasing nuclear charge in a one-electron ion leads to contraction of the orbital and an increase in binding energy of the electron. For example: He+, Li2+ <r>= n2a0/Z Where a0 is Bohr radius, the average radius of a 1S orbital in hydrogen. Z: atomic number En= -Z2R/n2 Hydrogenic ions A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  28. INORGANIC CHEMISTRY Section A3 A3 MANY-ELECTRON ATOMS Putting electrons into orbitals similar to those in the hydrogen atom gives a useful way of approximating the wavefunction of a many-electron atom. The electron configuration specifies the occupancy of orbitals, each of which has an associated energy. Orbital approximation Electron configuration Orbital energy The orbital approximation

  29. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Electrons have an intrinsic rotation called spin, which may point in only two possible directions, specified by a quantum number ms. Two electrons in the same orbital with opposite spin are paired. Unpaired electrons give rise to paramagnetism. Spin Quantum numbers ms=+1/2, -1/2 Electron spin A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  30. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 When the spin quantum number m, is included no two electrons in an atom may have the same set of quantum numbers. Thus a maximum of two electrons can occupy any orbital. Li : (1s)2 (2s)1 Pauli exclusion principle A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  31. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 The electrostatic repulsion between electrons weakens their binding in an atom, this is known as screening or shielding. The combined effect of attraction to the nucleus and repulsion from other electrons is incorporated into an effective nuclear charge. En= -Zeff2R/n2 σ = Z-Zeff Effective nuclear charge A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  32. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 An orbital is screened more effectively if its radial distribution does not penetrate those of other electrons. For a given n, s orbitals are least screened and have the lowest energy; p, d,... orbitals have successively higher energy. Degenerate Penetrating Screening and penetration A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  33. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 When filling orbitals with l>0, the lowest energy state is formed by putting electrons so far as possible in orbitals with different m values, and with parallel spin. Hund’s first rule A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  34. INORGANIC CHEMISTRY Section A4 A4 THE PERIODIC TABLE The periodic table - with elements arranged horizontally in periods and vertically in groups according to their chemical similarity - was developed in an empirical way in the 19th century. A more rigorous foundation came, first with the use of spectroscopy to determine atomic number and, second with the development of the quantum theory of atomic structure. History

  35. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A4 Building up The 'aufbau' or 'building up' principle gives a systematic method for determining the electron configurations of atoms and hence the structure of the periodic table. Elements in the same group have the same configurati0n of outer electrons. The way different orbitals are filled is controlled by their energies (and hence their different screening by other electrons) and by the Pauli exclusion principle. According to the aufbau principle, the ground-state electron configuration of an atom can be found by putting electrons in orbitals, starting with that of lowest energy and moving progressively to higher energy. （1） the lowest energy （2）Pauling exclusion principle （3）Hund’s rule A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  36. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A4 Penetration effect Screening effect. A3 THE NUCLEAR ATOM Intervening of energy level An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  37. INORGANIC CHEMISTRY Section A4 Electron configuration: The outmost electron configuration: Valence electron configuration:

  38. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A4 The table divides naturally into s, p, d and f blocks according to the outer electron configurations. s and p blocks form the main groups, the d block the transition elements, and the f block the lanthanides and actinides. Block structure A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  39. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A4 Group numbers and names Modern group numbering runs from 1 to 18, with the j bl0cks being subsumed into group 3. Older (and contradictory) numbering systems are still found. Some groups of elements are conventionally given names, the most commonly used being alkali metals (group l), alkaline earths (2), halogens (17) and noble gases (18). Alkali metal : rare earth: Alkaline metal: lanthanide: Transition metal: actinide: Coinage metal: Chalcogen: Halogen: Noble gas: A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  40. INORGANIC CHEMISTRY Section A5 A5 TRENDS IN ATOMIC PROPERTIES Energy and sizes Trends in orbital energy and size reflect changes in the principal quantum number and effective nuclear charge. They are seen experimentally in trends in ionization energy (IE) and apparent radius of atoms. From: En= -Zeff2R/n2 Ionization energy: E∞-E1=R To Average radius <r>=n2a0/Zeff Metallic radii: Covalent radii: Ionic radii: Van der Waals’ radii:

  41. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A5 Increasing nuclear charge causes a general increase of IE and a decrease of radius across any period. Breaks in the IE bend are found following the complete or half filling of any set of orbitals. Horizontal trends A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  42. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A5 Vertical trends A3 THE NUCLEAR ATOM A general increase of radius and decrease in IE down most groups is dominated by the increasing principal quantum number of outer orbitals. Effective nuclear charge also increases, and can give rise to irregularities in the IE trends. An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  43. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A5 States of ionization A3 THE NUCLEAR ATOM IEs for positive ions always increase with the charge. M2+, M3+, …., second, third,…. An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  44. INORGANIC CHEMISTRY Section A5 Electron affinity of an atom: defined as the ionization energy of the negative ion, thus the energy input in the process: M- M + e-

  45. INORGANIC CHEMISTRY Section B1 Section B Introduction to inorganic substance B1 ELECTRONEGATIVITY AND BOND TYPE Definition Electronegativity is the power of an atom to attract electrons to itself in a chemical bond. Elements of low electronegativity are called electropositive. Pauling Electronegativity: based on bond energies Mulliken Electronegativity: the average of the first ionization energy and the electron affinity of an atom. Allred-Rochow Electronegativity: proportional to Zeff/r2.

  46. INORGANIC CHEMISTRY Section B1 Different numerical estimates agree on qualitative trends: Electronegativity increases from left to right along a period, and generally decreases groups in the periodic table.

  47. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Section B1 The bonding triangle Electronegativity elements form meta1lic solids. Electronegative elements form molecules or polymeric solids with covalent bonds. Elements of very different electronegativity combine to form solids that can be described by the ionic model. Delocalization of electrons: Covalent compounds: Giant covalent lattices (Polymeric solids): Localized bonds: Cation： Anion： A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  48. INORGANIC CHEMISTRY Section B1

  49. INORGANIC CHEMISTRY INORGANIC CHEMISTRY Section A3 Section B1 The polarity of a bond arises from the unequal sharing of electrons between atoms with different electronegativities. There is no sharp dividing line between polar covalent and ionic substances. Homopolar(A covalent between two atoms of the same ELs) Bond polarity Heteropolar (A covalent between two atoms of the different ELs) Electric dipole moment Bond polarity A3 THE NUCLEAR ATOM An atom consists of a very small positively charged nucleus, surrounded by negative electrons held by electrostatic attraction. The motion of electrons changes when chemical bonds are formed, nuclei being unaltered. Electron and Nuclei Nuclei contain positive protons and uncharged neutrons. The number of protons is the atomic number (Z) of an element. The attractive strong interaction between protons and neutrons is opposed by electrostatic repulsion between protons. Repulsion dominates as Z increases and there is only a limited number of stable elements. Nuclear structure

  50. INORGANIC CHEMISTRY Section B2 B2 CHEMICAL PERIODICITY Major chemical trends, horizontally and vertically in the periodic table, can be understood in terms of changing atomic properties. This procedure has its limitations and many details of the chemistry of individual elements cannot be predicted by simple interpolation from their neighbors. Introduction

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