CHEM 3331 1nd Edition Lecture 1Outline of Current Lecture I. IntroductionII. Electron configurationIII. Bonding IV. Electronegativity Current LectureI. IntroductionOrganic Chemistry is the study of compounds. Wöhler was able to synthesize ammonium cyanate into urea. This was the birth of synthesis in 1828. Synthesis is the ability to make and/or break bonds between molecules to make complex molecules.Mechanisms explain how chemical reactions occur.Structure refers to how atoms are arranged for molecules.What makes carbon so unique? It is able to bond almost infinitely with itselfWhat is contained in an atom?Electrons (e )- mass 0, charge= -1ˉ Protons (p+)- mass=1, charge= 1Neutrons (n)- mass=1, charge= 0The nucleus contains protons and neutrons and is surrounded by a cloud of electrons.The atomic number tells how many protons and electrons an atom contains. The atomic mass helps determine how many neutrons our atom contains.An isotope is an atom with the same number of protons, but a different number of neutrons from the periodic table element. Carbon-12 contains 6 protons and 6 neutrons. Radioactive Carbon-14 contains 6 protons and 8 neutrons. Where exactly are electrons found?These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.The Heisenburg Uncertainty Principle states that the more precisely we know the position of an electron we are less likely to know its momentum. We can know where and electron is or how fast it is moving, but we cannot know both.Quantum numbers indicate the orbitals in which electrons are assigned. We indicate these as n. n=1 has a 1s orbital that contains 2e .ˉN=2 has a 2s orbital and 3(2p) orbitals. Each orbital contains 2e . Therefore, the n=2 has a total ˉof 8e .ˉThe s orbital is spherically symmetrical.The p orbital has three configurations since it lies on a three-dimensional plane. As we can see there is a p orbital that corresponds to each axis.II. Electron ConfigurationThere are 3 principles for electron configuration.Aufbau: lower energy orbitals are filled first. 1s before 2s before 2p before 3s and so on.Pauli Exclusion Principle: only 2e can occupy one orbital and they must have opposite spins.ˉHundt’s Rule: if 2 or more orbitals are empty, place e in each empty orbital until all are half full.ˉ(Graphic representation on next page)As we can see for nitrogen if we paired electrons up we would have 1 filled 2p orbital, 1 half-filled, and one empty. Using Hundt’s Rule we take the electron from the full 2p and give one electron to the empty orbital. Thus giving us three half-filled 2p orbitals.Why is e configuration so important?ˉAtoms share or transfer e to atain a filled shell of e when bonding. Therefore, the correct ˉ ˉconfiguration is needed to determine how many e can be shared or transferred for bonding.ˉIII. BondingIonic: e are transferred to create charged species. For example LiF.ˉLithium gives up an e to give fuorine an octet to stabilize the atom and bond lithium and ˉfuorine together.Covalent: the most common bonding in organic compounds. The e are shared between 2 ˉatoms. For example H2 and N2.As we can see the atoms don’t transfer e they share them to create pairs and reah their ˉrequired octet.IV. ElectronegativityIf the atoms are the same, such as H2 then the e are shared equally. This is called non-polar ˉcovalent. If the atoms differ, such as CCl the charges will differ slightly according to the atoms electronegativity. Electronegativity determines the e shif, creating a direction of polarity (dipole).ˉElectronegativity is the pull of e to an atom.ˉElectronegativity increases as we move upwards and to the right on the periodic table.H=-2.2 Li=-1.0 B=-1.8 Al=-1.6 C=-2.5 Si=-1.9 F=-4.0 Cl=-3.2 According to these electronegativities, Chlorine will pull the e closer to itself creating a ˉpolarity. The arrows show where the electrons are being pulled to.The above representation is of a non-polar compound because the dipoles cancel out. An example of a polar molecule with electronegativity is