H -|- C -|. .- N -|. .- O -. .. .- Cl :. .Lecture 1Outline of Current Lecture I. Atomic structureII. Electron configurationIII. Lewis Dot StructuresCurrent LectureA. I. Atomic Structure Nucleus: protons (+) and neutrons (neutral)Electron cloud: electrons (-) are located here. Cannot move freely. They are more in shells or energy levels. Each shell contains 2n2 electrons, where n = # of the shell.CHEM 333 1st Editiona. Shell 1 -> 2(1)2 = 2 electronsb. Shell 2 -> 2(2)2 = 8 electronsc. Shell 3 -> 2(3)2 = 18 electronsd. Shell 4 -> 2(4)2 = 32 electronsB. Subshells: Each shell is broken into subshells (s, p, d, f)a. Mainly focus on valence (outer shell) electrons because these are the electrons that are involved in bonding and give an atom its chemical propertiesC. Orbitals: regions of space that holds two electronsa. Electron configuration: description of electrons in obitals (number and where)b. Ground state configuration: lowest energy level (configuration)II. Rules to determine electron configuration:A. Aufbau Principle (“Build Up”): fill lowest energy orbitals firts (1s -> 2s -> 2p -> 3s)B. Pauli Exclusion Principle: only two electrons per orbital and spins must be opposite (electrons have magnetic north and south poles, so you need one ofeach)a. Example: 4 e- -> 1s2 2s2b. Example: 10 e- -> 1s2 2s2 2p6A. Hund’s Rule: Add one electron to each orbital equal in energy first. This minimizes electron repulsion.a. Example: b. Example:III. Lewis Dot Structure: element surrounded by dots to equal the number of electrons in the valence shellA. Examples:B. Octet Rule: want eight electrons because they are very stable and have noble gas configuration. Chemical bonds form in an attempt to complete the octet through sharing electrons between atoms.a. Complete the octet by:i. Lose or gain electrons (become ionic)1. anion: gain 1 electron (negative charge)2. cation: lose 1 electron (positive charge)ii. Share electrons with 1 or more atoms1. Covalent bond: a chemical bond between atoms by sharing electrons pairsC. Nonbonding elections: electron pairs not involved in bonding (O, N, Cl, F, Br, I)a. Example chart to show bonds and lone pairs:H - |- C -|. .- N -|. .- O -. .. .- Cl :. .# of bonds 1 4 3 2 1# of lone pairs 0 0 1 2
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