Chemistry Instructional Guide

Chemical Reactions

Chemistry

Quarter 3

HMHUnit 4

● Predict the relative number of atoms in the reactants versus the products at the atomic molecular scale ● Describe the molar ratios between different substances in the reaction ● Calculate the mass of any component of a reaction, given any other component Analysis Students describe how the mathematical representations (e.g., stoichiometric calculations): ● Show that the number of atoms or number of moles is unchanged after a chemical reaction where a specifc mass of reactant is converted to product ● Support the claim that atoms, and therefore mass, are conserved during a chemical reaction ● Students describe how the mass of a substance can be used to determine the number of atoms, molecules, or ions using moles and mole relationships (e.g., macroscopic to atomic molecular scale conversion using the number of moles and Avogadro’s number). Standard 4.1 What does it look like to demonstrate profciency on this standard? Developing the claim Students develop a claim that is supported by multiple sources of evidence, which includes the following idea: ● Whether a reaction absorbs or releases energy ● Reactions that release energy result in the temperature of the surroundings increasing and reactions that absorb energy results in the temperature of the surroundings decreasing. Identifying scientifc evidence Students identify and describe evidence supporting a claim, related to the transformation of energy, which could include: ● The starting and ending temperature of the surroundings ● An energy diagram, showing the relative potential energy of reactants and products ● An appropriate table of bond energies Evaluating and critiquing the evidence Students evaluate the evidence and include the following in their evaluation: ● A statement regarding potential sources or error in their data such as transfer of heat to outside of the system Reasoning and synthesis Students make and defend a claim using oral or written logical arguments regarding the transfer of energy, which could include: ● Identifying the reaction, the system, and the surroundings under study ● The bonds that are broken and the bonds that are formed during the course of the reaction

● The energy transfer between the system and the surroundings ● The relative potential energies of the reactants and the products Standard 4.5 What does it look like to demonstrate profciency on this standard? Developing the claim