Chemistry 101 1st Edition Exam 2 Study Guide Chapters 3 5 Lecture 1 Chapter 3 ElectronOrbitals and Shapes of Orbitals Qualitatively interpreted wavefunctions relate number of wavefunction nodes to n relate the shape of a wavefunction to l relate the orientation of a wavefunction to m l Probability of the placement of the atom is represented by Probability of electron density of an atom being somewhere in the orbital DECREASES as the radius widens Wave function 2 Radial Distribution Function The radial distribution function represents the TOTAL and ACTUAL probability of finding an electron within a thin spherical shell at distance r Note to think about the probability density vs radial distribution function o Probability density is where the electron is theoretical most likely to be Radial distribution function is the actual probability of finding a electron at a certain place A bump in the graph for the radial distribution is called a node Number of nodes high points n 1 for all types of orbitals L 0 s orbitals One value for m l 0 Lowest energy orbital in principal energy state L 1 porbitals m l 1 0 1 so you have 3 p orbitals o m l 1 px 0 py 1 pz L 1 d orbitals m l 2 1 0 1 2 so there are 5 d orbitals o d xy d xz d yz d x2 y2 d z2 Mainly four lobed except for d z2 which is two lobed with a toroid Why are atoms spherical Because they have many different shapes of orbitals that are all able to be contained in one large sphere Lecture 2 Chapter 4 Periodic Table and Electron Configurations Understand The Aufbau rule Pauli Exclusion principle Hund s rule Draw orbital diagrams and electronic configurations for main group elements Medeleev 1834 1907 Ordered the elements by atomic mass Saw a repeating pattern of properties Periodic law when the elements are arranged in order of increasing atomic mass certain sets of properties recur periodically Can use this arrangement of atoms to predict the patterns Electron Spin Electrons have an intrinsic property called spin o As they spin they generate a magnetic field o Either spin north or south 1 2 or 1 2 Pauli Exclusion Principle No two electrons can have the same four quantum numbers Ex o N 1 o L 1 o M l 1 o M s 1 2 Aufbau Principle Used to determine the order in which electrons fill the orbitals order is shown to the right Hund s Rule When filling electron degenerate orbitals electrons fill them singly first with parallel spins Filling each orbital with one electron and then pairing the electrons Example Summarizing orbital filling Electrons occupy orbitals so as to minimize energy of the atom therefore lower energy orbitals fill first in the order 1s 2s 2p 3s 3p 4s 3d 4p and so on Orbitals can hold no more than two electrons each and when two electrons are in the same orbital they have opposite spin pauli exclusion principle When orbitals of identical energy are available electrons first occupy these singularly with parallel spin rather than in pairs hund s rule Be able to draw electron diagrams S orbitals can hold 2 p orbitals can hold 6 d orbitals can hold 10 and f orbitals can hold 14 Lecture 3 Chapter 4 Valence Electrons and the Periodic Table Determine the valence electrons of an atom Recognize the relationship between valence electrons and the shape of the periodic table The differences between metals nonmetals and metalloids Valence electrons are those with all the sublevels with highest principal energy shell All other atoms are referred to as core electrons Note be able to determine valence electrons from the periodic table Groups on the periodic table Metals Tend to loose electrons during a chemical reaction o Shiny malleable good conductors of heat and electricity o Lower left side of periodic table and parts of the middle NonMetals Tend to gain electrons during a chemical reaction o Dull brittle poor conductors of heat o Upper right side of the periodic table Metalloids Properties of both metals and nonmetals Semiconductors Consist of only a few elements Alkali Metals Elements that have a valence shell consisting of a single electron in a s orbital Alkaline Earth Metals Valence shell has 2 electrons in an s orbital and wants to loose both of those electrons Halogens Just in need of one more electron to be like a noble gas full valence shell Chalogens 2 electrons short of a noble gas Cations vs Anions Cations form when atom loses electrons to form a positive atom Anions form when atom gains electrons to form a negative atom Lecture 4 Chapter 4 Periodic Trends Explain the following periodic properties o Effective nuclear charge o Trends in atomic radii o Trends in ionic radii o Trends in ionization energy o Ionization pattern of elements o Trends in metallic character Shielding In multi electron system electrons are simultaneously attracted to nucleus and repelled by each other Effective Nuclear Charge The effective nuclear charge is the net positive charge that is attracting a particular electron The attraction between nucleus and electron increases with increasing magnitude of nuclear charge You can find effective nuclear charge with the equation o Z effective Z S Z means actual nuclear charge S is charge screened by other electrons Otherwise known as the electrons in the core shell and whether they lose them or gain more to have a full valence shell Example beryllium Z effective 4 2 2 Atomic Radius and Trends Exception is in the transition elements Ionic Radius As the atoms become ions the size of the atom becomes significantly smaller if a cation Anions cause the atom to become larger adding electrons Ionization Energy Trends Ionization Energy is the energy needed to remove an electron from the atom or ion Is the OPPOSITE of the trends in atomic radius Note that when all three orbitals have one electron in it the ionization for the next atom will go slightly down this is because with three half full orbitals the pull to keep all is strong Explanation for figure above Ionization energy soars way higher when attempting to remove core electrons those not in the valence shell Electron Affinity Higher for those atoms that will most likely become anions Key IT IS HARD TO PREDICT Usually negative because an atom releases energy when it gains an electron 0 means that it has no electron affinity Metallic Character Remember this table Metallic means they are good conductors They can be flat sheets Can be made into wires Lecture 5 Chapter 5 Lewis Structures Classify a compound as ionic metallic or covalent Draw Lewis dot diagrams of