CHM 103 1st Edition Exam 3 Study Guide Lectures 18 25 Lecture 18 March 9 The n quantum number is the energy and distance from the nucleus and can be 1infinite The l quantum number is equal to n 1 The m quantum number is equal to L Lecture 19 March 12 In order to find out how electrons sit in orbitals you need to know the number of electrons number of electrons per orbital and energy of orbitals Electron spin is Qn and is either or 1 2 Pauli exclusion principle is where no two electrons on a single atom can have the same set of four quantum numbers To find out how orbitals increase in energy use the tree approach Orbital diagrams are the boxes you draw Lecture 20 March 23 Condensed electron configurations are where you go 1s 2 2s 2 Hunds rule is where electrons will try to maximize their overall spin whenever possible Core electrons are the ones close to the nucleus and have a noble gas configuration Valence electrons are electrons that participate in chemical reactions Effective nuclear charge is the number of protons and electrons you actually see and increases as you go to the top right corner Atomic radius also increases when you go to the top right corner Lecture 21 March 25 Ionic radii is similar to atomic radius Cations take an electron out of partially filled subshells except transitions Anions put an electron in an empty space in the outermost subshell Ionization energy is the energy needed to remove an electron Removing an electron takes energy so all ionization energies are positive and get more positive as you remove more and more Lecture 22 March 27 Electron affinity is the opposite of ionization energy Its easier to add an electron to a small atom because it s very low energy Metallic character answers how much does an element behave like a metal Lewis dot strcutures are used to show what a compound looks like Lecture 23 March 30 Electronegativity increases as you go to the top right corner A pure covalent bond has EN of 0 4 Polar covalent has EN of 4 2 Ionic bond has EN of over 2 Most covalent bonds are polar covalent Lecture 24 April 1 Resonance structures are structures that are equally as effective as the right Lewis structure Structures related by resonance blend together to form true structures Formal charges determine if the Lewis structure that makes physical sense The formal charge is the charge an atom would have in a molecule if bonded electrons are divided equally The sum of all formal charges should be zero for the right Lewis structure Lecture 25 April 3 You can draw electrons by VSEPR which is computerized A bond angle is the angle made by binding nuclei of atoms in a molecule