CHEM 1211 Exam 3 Study Guide Lectures 14 17 Chapters 5 7 Lecture 14 March 6 I Hess s law continued H f 1N2 g O2 G 1N2O g 1Na s Cl2 g 1NaCl s Use standard states EXOTHERMIC H rxn n H f products n H f reactants Trying to get to low energy state 1 H C3H8 104 7 KJ mol H CO2 393 5 KJ mol H O2 0 0 KJ mol H H2O 285 8 KJ mol Calculate the H 298 for this reaction C3H8 g 5O2 g 3CO2 g 4H2O l II III H rxn 3 393 5 4 285 8 1 104 7 H rxn 2 219 KJ mol EXOTHERMIC Chapter 6 Atoms Electronic Structure Color in Neon Lights Fireworks etc Use Barium Copper Strontium molecular compounds lightning bugs A Properties of Light photon Osolating electric field Wavelength m cm nm A A 1 x 10 10m or 1 x 10 8cm Period unit is seconds Frequency V 1 P V Frequency of Hertz Hz P Period Velocity v u wavelength U frequency in Hz V velocity in m s or cm s IV EX VACUUM 3 0 x 108 m s or 3 0 x 1010 cm s Constant Frequency Variable Wavelength Distance Frequency of photon is constant A Photoelectric Effect lights can strike the surface of some metals causing an e to be ejected Work fxn hvo WAVE PARTICLE DUALITY B Light Energy 1900 Max Planck black body radiation 1 Energy is quantized 2 Light has particle character E hv or E hc or E nhv H 6 626 x 10 34 J x S Ephoton or 1 Lecture 15 March 18 I Electromagnetic Radiation A Emission Spectrum formed by electric current passing through a gas in a vacuum tube at a very low pressure which causes gas to emit light Ex Prism Light Prism Detector If we add lots of energy to a sample of elemental gas we get an emission spectrum elemental specific 1 In the hydrogen emission spectrum a band is observed at 4860A What is the frequency and energy of this emission line C v V C 4860A 1 x 10 10m 4 860 x 10 7m 1A V visible green light 3 00 x 108 m s 6 17 x 1014 s 1 nHz 4 860 x 10 7m E hv E 6 626 x 10 34 J s 6 17 x 108 m s 4 088 x 10 19 J photon 4 088 x 10 19 J 6 02 x 1023 2 46 x 105 J mol photon photon Mol photon E 246 KJ mol photon B Absorption Spectrum shine a bean of white light through gas Indicates wavelengths of light that have been ABSORBED II III C Bohr Model of Atom only works for hydrogen explains atomic spectra Energy of quantized state RhC n2 N integral numbers only 1 to infinity Radius of orbitals n2 0 0529nm Predicting Emission Lines of Hydrogen A Rydberg Equation 1 RH 1 1 n12 n22 RH 1 097 x 107 m 1 RH 1 097 x 10 2 nm 1 n refers to one of the infinite possible energy state of the electron in hydrogen requirement n1 n2 Electronic Transitions 1 Move an electron from a lower energy level to a higher energy level E RhC 1 1 n12 n22 2 Start a rotational mode of motion 3 Begin a vibrations mode of motion 4 Gain kinetic energy translational motion ex water A Wave nature of electrons 2 r n DE Broglie said the wavelength of an object h mv 2 r nh mv Angular momentum mvr nh 2 Lecture 16 March 20 I Orbital Quantum Number An atomic orbital is defined by three quantum numbers N shell principle L Angular Momentum Quantum Number Ml Designates an orbital within a shell Electrons arranged in shells and subshells made of orbitals You cannot figure out Ml without L or L without N 1 Clicker Question One Calculate Enthalpy H f for H2S g given that Enthalpy H fO2 0 KJ mol Enthalpy H fSO2 296 8 KJ mol Enthalpy H fH2O 285 8 KJ mol Enthalpy H 298 1124 KJ mol Answer 20 6 KJ 2 Clicker Question Two Which is not a possible value for the principle quantum number A 4 B 2 C 1200 D 0 3 Clicker Question Three Consider the third shell in Hydrogen How many values of the angular momentum quantum number would be possible A 0 B 1 C 2 D 3 E 4 A The S Orbital The 1st shell has n 1 lowest energy SO l 0 ml 0 Since ml has a single value the subshell has a single orbital This subshell is labeled S and we call this orbital 1S it has a spherical shape State with the lowest energy state first when dealing with electrons B The P Orbital For n 2 l 0 and 1 Two types of orbitals 2 subshells II For l 0 ml 1 0 1 this is the p subshell with three orbitals When l 1 there is a planar node through the nucleus Planar node spot on orbital where the probability of find the electron is zero Px Py Pz Degenerate have same energy C The D Orbital third shell 2 planar nodes For l 2 ml 2 1 0 1 2 D subshell with five orbitals Number of nodes value of angular quantum number l There are n2 orbitals in the nth shell Spin Quantum Number Last Quantum number is the spin quantum number Ms The spin quantum number values Ms 1 2 or 1 2 Quantum number tells us the spin and orientation of the magnetic field of the electron Wolfgang Pauli 1925 Exclusion Principle NO two electrons in an atom can have the same set of four quantum numbers Orbitals can only have two electrons max Doesn t have to have two electrons though 1 Clicker Question Four Which of these subshell types isn t possible A 5s n 5 l 0 B 4p n 4 l 1 C 3d n 3 l 2 D 2d n 2 l 2 E 2p n 2 l 1 Lecture 17 March 25 I Using a Clicker for Spins A Spin V Spin Separating Orbitals AV AV A Clicker Question One II What quantum number would be used to determine the number of orbitals in a subshell A Angular Momentum Quantum Number B Magnetic Quantum Number C Principle Quantum Number D Spin Quantum Number B Clicker Question Two The angular momentum quantum number for a subshell is four How many orbitals would we expect to find A 10 B 4 C 6 D 16 E 9 C Clicker Question Three What type of orbital is this G D Clicker Question Four When filling three degenerate orbitals with two electrons you must first A Utilize Pauli Exclusion Principle B Throw them in Jail C Understand DE Broglie s Principle D Apply Hund s Rule Electron Configurations for Helium Z 2 2px energy 2py 2pz 2s 1s 1s Orbital Box Notation 1s Core electron 2s Valence Outer Shell electron Lithium 1s2 2s1 Valence He 2s1 …