Inorganic Lecture 1

Inorganic Lecture 1 - Introduction to Inorganic Chemistry...

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Unformatted text preview: Introduction to Inorganic Chemistry What is Inorganic Chemistry? Inorganic Chemistry... Chemistry... embraces all of the elements is comprised of materials with widely differing properties, structures and reactivities is not an isolated discipline includes a greater variety of materials than organic chemistry 1 Inorganic versus Organic Inorganic Includes all elements Organic Primarily the chemistry of carbon specifically when bound to H,N,O,S,X and a few other elements Most usually molecular Maximum coordination = 4 Atomic, molecular and extended structures Maximum coordination up to 14 Classes of reactions, sometimes mechanism are unnecessary or impossible Mechanisms usually known Types of Inorganic Substances 1. 2. 3. 4. 2 1. Elements Their Structures are..... are... Atomic Molecular gases and liquids Molecular solids Covalent Extended Structures Metallic Extended Structures Solids Liquids 3 The crystal structure of diamond 2. Ionic Compounds Example: Table Salt, NaCl 4 The crystal structure of NaCl 2. Ionic Compounds Another Example: The Mineral Stibnite, Sb2S3 5 The crystal structure of stibnite 6 Atomic Structure Chapter 1 sections 1-9 Some review of basic concepts Fundamental Particles of an Atom _______ mass negligible mass mass + charge - charge NO charge in nucleus around nucleus in nucleus ______ ______ All atoms have an equal number of protons and electrons - they are neutral Most of the weight of an atom is in the nucleus Most of the volume of an atom is around nucleus The number of protons and electrons defines the element, but the neutrons may vary 7 A Z E The atomic number defines an element The atomic number (Z) = # of protons = # of electrons The mass number (A) = number of protons + number of neutrons A-Z = number of neutrons A particular element can have different numbers of neutrons (different mass #). These are its isotopes, for example 12C, 13C, 14C The relative atomic mass of an element takes into account its various isotopes and their natural abundance Electronic Structure of an Atom What is it? The number and distribution of electrons about a central nucleus Why do we care? The electronic structure of an atom tell us a lot about its properties The electronic structure of the atoms is important in understanding periodic trends. 8 What is an electron? A particle? A wave? How about both? Wave-Particle Duality Where is the electron? Heisenberg uncertainty principle It is impossible to know exactly both the momentum and position of the electron at the same time So, we don't define exactly where it is, instead we describe don' the probability of finding the electron in a certain volume of space This is determined from the mathematical function 2, where is the wave function You will go further into this in P-Chem class, for now we will try to understand the consequences of this 9 How do we define where an e- resides? 4 principle quantum numbers: n, l, ml, ms n = the principle quantum number Takes on integer values Can be thought of as energy levels based on distance from the nucleus n = 1, 2, 3, 4 ... It tells us the shape of the orbital s orbital l=0 p orbital l=1 d orbital l=2 f orbital l=3 l = orbital quantum number How do we define where an e- resides? ml = magnetic quantum number Corresponds to the orientation of the orbital on an x, y, z coordinate system ml has the values from -l to +l ms = the spin quantum number Either +1/2 or -1/2 10 Electrons in the 1s Orbital An s-orbital is spherical and symmetric The sign everywhere is positive n = __, l = __, ml = __ Significance of the sign (shading or +/-) indicates the sign of the wave function () for an electron ( represented by a wave Electrons in the 2p Orbitals n = __, l = __, ml = _______ Three possible orientations in space All have a node (zero electron density) at the nucleus Orbitals with equal energies are called degenerate 11 Electrons in 3d Orbitals n = __, l = __, ml = _________ Five possible orientations in space The five d orbitals have the same energy (they are degenerate) These orbitals are more complicated 3d orbitals ___ symmetrical about the z-axis _____________ are alike except that they have their lobes in different planes _______ has the same shape as the dxy but it rotated 45 about the z-axis. So, its lobes 45 lie directly on the x- and y-axes instead of in between 12 d-Orbitals Electrons in f-Orbitals n = __, l = __, ml = ____________ Even more complicated Only important for f-block elements Lanthanides Actinides 13 Ground State Electron Configuration of the H Atom The energy of the atomic orbitals increases with increasing n The energy of an e- is the same no matter if it is in an s, p, d or f orbital as long as the principle quantum # is the same (this is because there is only one e !) Ground State Electron Configuration of the H Atom Ground state - the most energetically favorable state A single electron occupies the 1s orbital 1 1s 14 Ground State Electron Configuration of Many e- Atoms We have to consider more things The repulsions among electrons How those electrons are feeling the positive charge of the nucleus Here the energy of an electron changes when it is in different kinds of orbitals (different values of l) Ground State Electron Configuration of Many e- Atoms An orbital is fully occupied when it contains two electrons which are spin-paired Before pairing we first put one e- into each degenerate orbital The spreading out of e density gives extra stability to the e- in question as well as the entire collection of e-s 15 Electron Filling 1s 2s 3s 4s 5s 6s 7s 2p 3p 4p 5p 6p 3d 4d 4f 5d 5f 6d Orbitals are filled in order of energy, the lowest Energy orbitals are filled first Electrons are added to degenerate orbitals until each orbital contains one electron, then the electrons are paired No two electrons can have the same exact set of quantum numbers Electron Filling The filling of electrons occurs in shells (think of rows in the periodic table) First shell K 1s Second shell L 2s, 2p Third shell M 3s, 3p Fourth shell N 4s, 3d, 4p 16 Valence e-s Defined as the outer most shell of electrons All other electrons are considered core electrons Valence electrons are most important in determining the properties of an element 17 Let's Practice Electron Configurations Ge Sc Cr Ag 18 ...
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This note was uploaded on 04/07/2008 for the course CHEM 311 taught by Professor Aitken during the Spring '08 term at Duquesne.

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