Grades 9, 10, 11, 12

Science Practices

Course Content

Models and Representations

Question and Method

Representing Data and Phenomena

Model Analysis

Mathematical Routines

Argumentation

Atomic Structure and Properties

Molecular and Ionic Compound Structure and Properties

Intermolecular Forces and Properties

Chemical Reactions

Kinetics

Thermodynamics

Equilibrium

Acids and Bases

Applications of Thermodynamics

Describe models and representations, including across scales.

Describe the components of and quantitative information from models and representations that illustrate particulate-level properties only.

Describe the components of and quantitative information from models and representations that illustrate both particulate-level and macroscopiclevel properties.

Determine scientific questions and methods.

Identify a testable scientificquestion based on an observation, data, or a model.

Formulate a hypothesis or predict the results of an experiment.

Identify experimental procedures that are aligned to a scientific question (which may include a sketch of a lab setup).

Make observations or collect data from representations of laboratory setups or results, while attending to precision where appropriate.

Identify or describe potential sources of experimental error.

Explain how modifications to an experimental procedure will alter results.

Create representations or models of chemical phenomena.

Represent chemical phenomena using appropriate graphing techniques, including correct scale and units.

Represent chemical substances or phenomena with appropriate diagrams or models (e.g., electron configuration).

Represent visually the relationship between the structures and interactions across multiple levels or scales (e.g., particulate to macroscopic).

Analyze and interpret models and representations on a single scale or across multiple scales.

Explain chemical properties or phenomena (e.g., of atoms or molecules) using given chemical theories, models, and representations.

Explain whether a model is consistent with chemical theories.

Explain the connection between particulate-level and macroscopic properties of a substance using models and representations.

Explain the degree to which a model or representation describes the connection between particulate-level properties and macroscopic properties.

Solve problems using mathematical relationships.

Identify quantities needed to solve a problem from given information (e.g., text, mathematical expressions, graphs, or tables).

Identify an appropriate theory, definition, or mathematical relationship to solve a problem.

Explain the relationship between variables within an equation when one variable changes.

Identify information presented graphically to solve a problem.

Determine a balanced chemical equation for a given chemical phenomenon.

Calculate, estimate, or predict an unknown quantity from known quantities by selecting and following a logical computational pathway and attending to precision (e.g., performing dimensional analysis and attending to significant figures).

Develop an explanation or scientific argument.

Make a scientific claim.

Support a claim with evidence from experimental data.

Support a claim with evidence from representations or models at the particulate level, such as the structure of atoms and/or molecules.

Provide reasoning to justify a claim using chemical principles or laws, or using mathematical justification.

Provide reasoning to justify a claim using connections between particulate and macroscopic scales or levels.

Explain the connection between experimental results and chemical concepts, processes, or theories.

Explain how potential sources of experimental error may affect the experimental results.

Calculate quantities of a substance or its relative number of particles using dimensional analysis and the mole concept.

Explain the quantitative relationship between the mass spectrum of an element and the masses of the element's isotopes.

Explain the quantitative relationship between the elemental composition by mass and the empirical formula of a pure substance.

Explain the quantitative relationship between the elemental composition by mass and the composition of substances in a mixture.

Represent the electron configuration of an element or ions of an element using the Aufbau principle.

Explain the relationship between the photoelectron spectrum of an atom or ion and:

Explain the relationship between trends in atomic properties of elements and electronic structure and periodicity.

Explain the relationship between trends in the reactivity of elements and periodicity.

Explain the relationship between the type of bonding and the properties of the elements participating in the bond.

Represent the relationship between potential energy and distance between atoms, based on factors that influence the interaction strength.

Represent an ionic solid with a particulate model that is consistent with Coulomb's law and the properties of the constituent ions.

Represent a metallic solid and/or alloy using a model to show essential characteristics of the structure and interactions present in the substance.

Represent a molecule with a Lewis diagram.

Represent a molecule with a Lewis diagram that accounts for resonance between equivalent structures or that uses formal charge to select between nonequivalent structures.

Based on the relationship between Lewis diagrams, VSEPR theory, bond orders, and bond polarities:

Explain the relationship between the chemical structures of molecules and the relative strength of their intermolecular forces when:

Explain the relationship among the macroscopic properties of a substance, the particulate-level structure of the substance, and the interactions between these particles.

Represent the differences between solid, liquid, and gas phases using a particulatelevel model.

Explain the relationship between the macroscopic properties of a sample of gas or mixture of gases using the ideal gas law.

Explain the relationship between the motion of particles and the macroscopic properties of gases with:

Explain the relationship among non-ideal behaviors of gases, interparticle forces, and/or volumes.

Calculate the number of solute particles, volume, or molarity of solutions.

Using particulate models for mixtures:

Explain the relationship between the solubility of ionic and molecular compounds in aqueous and nonaqueous solvents, and the intermolecular interactions between particles.

Explain the relationship between a region of the electromagnetic spectrum and the types of molecular or electronic transitions associated with that region.

Explain the properties of an absorbed or emitted photon in relationship to an electronic transition in an atom or molecule.

Explain the amount of light absorbed by a solution of molecules or ions in relationship to the concentration, path length, and molar absorptivity.

Identify evidence of chemical and physical changes in matter.

Represent changes in matter with a balanced chemical or net ionic equation:

Represent a given chemical reaction or physical process with a consistent particulate model.

Explain the relationship between macroscopic characteristics and bond interactions for:

Explain changes in the amounts of reactants and products based on the balanced reaction equation for a chemical process.

Identify the equivalence point in a titration based on the amounts of the titrant and analyte, assuming the titration reaction goes to completion.

Identify a reaction as acid-base, oxidation-reduction, or precipitation.

Identify species as Brønsted-Lowry acids, bases, and/or conjugate acid-base pairs, based on proton-transfer involving those species.

Represent a balanced redox reaction equation using half-reactions.

Explain the relationship between the rate of a chemical reaction and experimental parameters.

Represent experimental data with a consistent rate law expression.

Identify the rate law expression of a chemical reaction using data that show how the concentrations of reaction species change over time.

Represent an elementary reaction as a rate law expression using stoichiometry.

Explain the relationship between the rate of an elementary reaction and the frequency, energy, and orientation of molecular collisions.

Represent the activation energy and overall energy change in an elementary reaction using a reaction energy profile.

Identify the components of a reaction mechanism.

Identify the rate law for a reaction from a mechanism in which the first step is rate limiting.

Identify the rate law for a reaction from a mechanism in which the first step is not rate limiting.

Represent the activation energy and overall energy change in a multistep reaction with a reaction energy profile.

Explain the relationship between the effect of a catalyst on a reaction and changes in the reaction mechanism.

Explain the relationship between experimental observations and energy changes associated with a chemical or physical transformation.

Represent a chemical or physical transformation with an energy diagram.

Explain the relationship between the transfer of thermal energy and molecular collisions.

Calculate the heat q absorbed or released by a system undergoing heating/cooling based on the amount of the substance, the heat capacity, and the change in temperature.

Explain changes in the heat q absorbed or released by a system undergoing a phase transition based on the amount of the substance in moles and the molar enthalpy of the phase transition.

Calculate the heat q absorbed or released by a system undergoing a chemical reaction in relationship to the amount of the reacting substance in moles and the molar enthalpy of reaction.

Calculate the enthalpy change of a reaction based on the average bond energies of bonds broken and formed in the reaction.

Calculate the enthalpy change for a chemical or physical process based on the standard enthalpies of formation.

Represent a chemical or physical process as a sequence of steps.

Explain the relationship between the enthalpy of a chemical or physical process and the sum of the enthalpies of the individual steps.

Explain the relationship between the occurrence of a reversible chemical or physical process, and the establishment of equilibrium, to experimental observations.

Explain the relationship between the direction in which a reversible reaction proceeds and the relative rates of the forward and reverse reactions.

Represent the reaction quotient Q_c or Q_p, for a reversible reaction, and the corresponding equilibrium expressions K_c = Q_c or K_p = Q_p.

Calculate K_c or K_p based on experimental observations of concentrations or pressures at equilibrium.

Explain the relationship between very large or very small values of K and the relative concentrations of chemical species at equilibrium.

Represent a multistep process with an overall equilibrium expression, using the constituent K expressions for each individual reaction.

Identify the concentrations or partial pressures of chemical species at equilibrium based on the initial conditions and the equilibrium constant.

Represent a system undergoing a reversible reaction with a particulate model.

Identify the response of a system at equilibrium to an external stress, using Le Châtelier's principle.

Explain the relationships between Q, K, and the direction in which a reversible reaction will proceed to reach equilibrium.

Calculate the solubility of a salt based on the value of K_sp for the salt.

Identify the solubility of a salt, and/or the value of K_sp for the salt, based on the concentration of a common ion already present in solution.

Identify the qualitative effect of changes in pH on the solubility of a salt.

Explain the relationship between the solubility of a salt and changes in the enthalpy and entropy that occur in the dissolution process.

Calculate the values of pH and pOH,based on K_w and the concentration of all species present in a neutral solution of water.

Calculate pH and pOH based on concentrations of all species in a solution of a strong acid or a strong base.

Explain the relationship among pH, pOH, and concentrations of all species in a solution of a monoprotic weak acid or weak base.

Explain the relationship among the concentrations of major species in a mixture of weak and strong acids and bases.

Explain results from the titration of a mono- or polyprotic acid or base solution, in relation to the properties of the solution and its components.

Explain the relationship between the strength of an acid or base and the structure of the molecule or ion.

Explain the relationship between the predominant form of a weak acid or base in solution at a given pH and the pK_a of the conjugate acid or the pK_b of the conjugate base.

Explain the relationship between the ability of a buffer to stabilize pH and the reactions that occur when an acid or a base is added to a buffered solution.

Identify the pH of a buffer solution based on the identity and concentrations of the conjugate acid-base pair used to create the buffer.

Explain the relationship between the buffer capacity of a solution and the relative concentrations of the conjugate acid and conjugate base components of the solution.

Identify the sign and relative magnitude of the entropy change associated with chemical or physical processes.

Calculate the entropy change for a chemical or physical process based on the absolute entropies of the species involved in the process.

Explain whether a physical or chemical process is thermodynamically favored based on an evaluation of ΔG̊.

Explain, in terms of kinetics, why a thermodynamically favored reaction might not occur at a measurable rate.

Explain whether a process is thermodynamically favored using the relationships between K, ΔG̊, and T.

Explain the relationship between external sources of energy or coupled reactions and their ability to drive thermodynamically unfavorable processes.

Explain the relationship between the physical components of an electrochemical cell and the overall operational principles of the cell.

Explain whether an electrochemical cell is thermodynamically favored, based on its standard cell potential and the constituent half-reactions within the cell.

Explain the relationship between deviations from standard cell conditions and changes in the cell potential.

Calculate the amount of charge flow based on changes in the amounts of reactants and products in an electrochemical cell.

The electron configurationof the species.

The interactionsbetween the electronsand the nucleus.

Explain structural properties of molecules.

Explain electron properties of molecules.

The molecules are of thesame chemical species.

The molecules are of twodifferent chemical species.

The kinetic moleculartheory (KMT).

A particulate model.

A graphical representation.

Represent interactionsbetween components.

Represent concentrationsof components.

For physical changes.

For given informationabout the identity of thereactants and/or product.

For ions in a givenchemical reaction.

Chemical processes.

Physical processes.