Understanding Molecular Geometry and Structures.pdf

🌐 9/8/24, 6:24 PM Understanding Molecular Geometry and Structures Molecular Geometry Molecules spread out their atoms as far away from each other as possible. This is known as the Valen...

🌐 9/8/24, 6:24 PM Understanding Molecular Geometry and Structures Molecular Geometry Molecules spread out their atoms as far away from each other as possible. This is known as the Valence Shell Electron Pair Repulsion (VSEPR) theory. Two-Dimensional vs. Three-Dimensional Geometry In a two-dimensional world, the furthest apart that four chlorine atoms can get on a flat surface is 90 degrees. However, in a three-dimensional world, each chlorine atom can spread out further than 90 degrees, resulting in a tetrahedral shape. Three Simple Geometries 📐 Number of Things Geometry 2 Linear 3 Trigonal Planar 4 Tetrahedral Hybridization 🔬 Hybridization is a change that atoms undergo to form bonds. Electron Geometry Bond Angle Linear 180° Trigonal Planar 120° Tetrahedral 109.5° Condensed Formulas 📝 A condensed formula is one that can be written on one line of type. A condensed formula is a way of representing a molecule using a single line of text, rather than drawing out the entire structure. Examples of condensed formulas: CH₃CH₂CH₂CH₃ (CH₃)₂CHCH₃ CH₃COCH₃ Sigma (σ) and Pi (π) Bonds 🔗 Single covalent bonds = one σ bond Double bonds = one σ bond + one π bond Triple bonds = one σ bond and two π bonds Bond Lengths and Strengths 📊 Triple bonds are shorter and stronger than double bonds, which are shorter and stronger than single bonds. Orbital Hybridization 🔬 sp³ orbitals are formed from one s orbital and three p orbitals. https://www.turbolearn.ai/content/196840d8-c8d6-4e91-bb65-6881be9d4781 1/2 9/8/24, 6:24 PM Understanding Molecular Geometry and Structures sp² orbitals are formed from one s orbital and two p orbitals. 🔄 sp orbitals are formed from one s orbital and one p orbital. Resonance Structures Resonance structures are different forms of a molecule that have the same arrangement of atoms, but different arrangements of electrons. Resonance structures are a way of representing the delocalization of electrons in a molecule. Resonance Structure Rules 📜 Only electrons move, not atoms. Electrons can move towards or into an atom that does not have a full octet. If an atom already has a full octet, electrons can only move into it if electrons are pushed out the opposite side. Major/Greatest Resonance Contributor? 🤔 The most stable resonance structure is the one that: 1. Has a full octet on every atom. 2. Has the smallest possible number of charges. 3. Has negative charges on the most electronegative atoms and positive charges on the least electronegative atoms. Cycloalkanes and Ring Strain ⭕️ Cycloalkanes are alkanes that are cyclic, or ring-shaped. Cycloalkanes are a type of hydrocarbon that have a ring structure. Cyclohexane is the Most Stable 🏆 Cyclohexane rings are very special because they are found in many real-life organic compounds. Cyclohexane is a type of cycloalkane that has a chair conformation, which is its most stable form. Drawing Chair Structures 📝 Chair conformations are drawn on paper with the ring in a chair-like shape. Axial and equatorial positions are labeled. Axial vs. Equatorial 🔄 Equatorial positions are more favorable than axial for larger groups because of 1,3-diaxial interactions. Trans vs. Cis Cyclohexanes 🔄 If two substituents are going in the same direction (both up or both down), they are cis to each other. If two substituents are going in opposite directions (one up and one down), they are trans to each other. https://www.turbolearn.ai/content/196840d8-c8d6-4e91-bb65-6881be9d4781 2/2