Master AP Chemistry Topic 4.5 with this free practice quiz. Test your skills on mole to mole ratios, limiting reactants, excess reactants, and theoretical yield to prepare for your AP exam. Coefficients Are Mole Ratios, Not Mass Ratios Stoichiometry is the arithmetic of a balanced equation: it converts an amount of one substance in a … Read more
One Competition Runs All Three Phases Every phase is the score of a single contest. Kinetic energy pulls particles apart and keeps them moving; intermolecular forces pull them together and hold them close. Temperature sets the average kinetic energy; the forces were priced in Topic 3.1. When the forces win clearly, particles lock into fixed … Read more
How to Use This Worksheet Work through the sections in order. Section A checks the ideas, Section B builds fluency with radii, densities, melting point data and identifications, and Section C mixes everything in exam style. Use the same two questions for every substance in this worksheet. First, what are the particles: ions, atoms in … Read more
Four Kinds of Solid, One Deciding Question Every solid is classified by two questions: what are the particles, and what holds them together? Ions held by electrostatic attraction give an ionic solid. Metal cations in a sea of mobile electrons give a metallic solid. Atoms joined into one continuous covalent structure give a covalent network … Read more
How to Use This Worksheet Work through the sections in order. Section A checks the ideas, Section B builds fluency with electron counts, data and rankings, and Section C mixes everything the way an exam would. Use the same three steps for every question. First, decide from the structure whether each particle is polar or … Read more
Forces Between Particles, Not Bonds Within Them Intermolecular forces are attractions between separate particles, one molecule to the next. The covalent bonds inside a molecule are intramolecular, and far stronger: an O-H bond costs 463 kJ/mol to break, against a few tens to pull two water molecules apart. When dry ice sublimes, the CO₂ molecules … Read more
How to Use This Worksheet Work through the sections in order. Section A checks the ideas, Section B builds fluency with individual molecules and ions, and Section C mixes geometry, hybridization, bonding and polarity the way an exam would. For every central atom, use the same working sequence and write down every step: count the … Read more
From a Lewis Diagram to a Three Dimensional Structure A Lewis diagram is flat, but a molecule is not. VSEPR theory turns the diagram into a three dimensional prediction by treating every region of electron density around a central atom as an electron domain. Domains repel through Coulombic repulsion and arrange themselves as far apart … Read more
How to Use This Worksheet Work through the sections in order. Section A checks the ideas, Section B builds fluency with formal charge audits and average bond orders, and Section C mixes everything the way an exam would. For every structure, audit in the same fixed order: count the total valence electrons, describe the bonds … Read more
When One Lewis Diagram Is Not Enough Some species cannot be represented honestly by a single Lewis diagram. Draw carbonate, CO₃²⁻, by the Topic 2.5 sequence and one C−O bond comes out double, the other two single, yet nothing picks out one oxygen for the double bond: any of the three could carry it. The … Read more