MTLE Chemistry (Grades 9-12) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Limiting reactant

The reactant consumed first in a chemical reaction; it determines the maximum amount of product that can form, calculated by comparing mole ratios from the balanced equation.

Mole ratio

The ratio of coefficients of two substances in a balanced chemical equation, used to convert moles of one substance into moles of another during stoichiometric calculations.

Molar mass

The mass in grams of one mole of a substance, numerically equal to its formula mass in atomic mass units, used to convert between grams and moles.

Percent yield

Actual yield divided by theoretical yield, multiplied by 100; it measures reaction efficiency and is always less than or equal to 100 percent in real experiments.

Ideal gas law

PV = nRT, relating pressure, volume, moles, and absolute temperature; R equals 0.08206 L·atm/(mol·K) and temperature must be expressed in kelvin.

Combined gas law

P1V1/T1 = P2V2/T2 for a fixed amount of gas; it combines Boyle, Charles, and Gay-Lussac relationships and requires absolute temperature in kelvin.

Dalton's law of partial pressures

The total pressure of a gas mixture equals the sum of the partial pressures of its individual gases, assuming no chemical reaction between components.

Calorimetry equation

q = mcΔT, where q is heat absorbed or released, m is mass, c is specific heat capacity, and ΔT is the temperature change in degrees Celsius or kelvin.

Hess's law

The enthalpy change of an overall reaction equals the sum of enthalpy changes of individual steps, allowing ΔH to be calculated from known thermochemical equations.

Bond energy

The energy required to break one mole of a specific bond in the gas phase; breaking bonds absorbs energy while forming bonds releases it.

Equilibrium constant

K equals the product of product concentrations raised to their coefficients divided by reactant concentrations raised to theirs, omitting pure solids and liquids.

Le Châtelier's principle

When a stress such as concentration change, pressure change, or temperature change is applied to a system at equilibrium, the system shifts to partially offset that stress.

pH definition

pH equals negative log of the hydronium ion concentration; at 25 degrees Celsius, pH plus pOH equals 14 because Kw is 1.0 times 10 to the negative fourteenth.

Buffer solution

A solution containing a weak acid and its conjugate base, or a weak base and its conjugate acid, that resists large pH changes when small amounts of acid or base are added.

Titration equivalence point

The point at which the moles of titrant added stoichiometrically equal the moles of analyte present; it is detected by an indicator color change or a pH curve inflection.

Oxidation and reduction

Oxidation is loss of electrons and reduction is gain of electrons; the two always occur together, with the oxidizing agent being reduced and the reducing agent oxidized.

Electrochemical cell

A device converting chemical energy to electrical energy; oxidation occurs at the anode and reduction at the cathode, with electrons flowing through an external circuit.

Standard cell potential

E°cell equals E°cathode minus E°anode using standard reduction potentials; a positive value indicates a spontaneous galvanic reaction under standard conditions.

Half-life

The time required for half of a radioactive sample to decay; remaining amount equals initial amount multiplied by one-half raised to the number of half-lives elapsed.

Alpha decay

Radioactive emission of a helium-4 nucleus, decreasing the mass number by four and the atomic number by two while producing a new element.

Beta decay

Emission of a beta particle from the nucleus, converting a neutron into a proton; mass number stays the same and atomic number increases by one.

Electron configuration rules

Aufbau fills lowest-energy orbitals first, Pauli exclusion limits each orbital to two opposite-spin electrons, and Hund's rule places unpaired electrons in degenerate orbitals before pairing.

Periodic trends

Atomic radius decreases left to right across a period and increases down a group; ionization energy and electronegativity show the opposite pattern.

Ionic versus covalent bonding

Ionic bonding involves electron transfer between metal and nonmetal forming ions; covalent bonding involves electron sharing, typically between nonmetals, creating discrete molecules or networks.

Molecular polarity

Polarity depends on both bond dipoles and molecular geometry; symmetric geometries such as linear CO2 or tetrahedral CH4 cancel dipoles and produce nonpolar molecules.

Intermolecular forces

London dispersion forces act on all molecules, dipole-dipole forces require polar molecules, and hydrogen bonding requires hydrogen attached to nitrogen, oxygen, or fluorine.

Solubility rules

Most nitrate, sodium, potassium, and ammonium salts are soluble; most silver, lead, and mercury salts are insoluble, allowing prediction of precipitation in double replacement reactions.

Colligative properties

Boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure depend on the number of dissolved particles, not on particle identity.

Reaction rate factors

Rate increases with higher concentration, higher temperature, greater surface area, and presence of a catalyst, which lowers activation energy without altering enthalpy change.

5E instructional model

A lesson sequence of engage, explore, explain, elaborate, and evaluate that places student investigation before formal explanation to support conceptual understanding.

Three-dimensional learning

Instruction combining disciplinary core ideas, science and engineering practices, and crosscutting concepts, as emphasized in current science education frameworks and state standards.

Formative assessment

Ongoing checks during instruction, such as exit tickets, whiteboard predictions, or particulate drawings, used to adjust teaching before summative evaluation occurs.