MTEL Chemistry flashcards
MTEL Chemistry · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Atomic number (Z)
- Number of protons in a nucleus; identifies the element and equals the electron count in a neutral atom.
- Mass number (A)
- Sum of protons and neutrons in a nucleus; isotopes of an element share Z but differ in A and neutron count.
- Valence electrons
- Electrons in the outermost principal energy level; they determine bonding, ion charge, and periodic trends in reactivity.
- Ionization energy trend
- Energy needed to remove an electron; increases across a period and decreases down a group as shielding and distance grow.
- Molarity
- Moles of solute divided by liters of solution; temperature-dependent because solution volume expands with heating.
- Dilution equation
- M1V1 = M2V2 relates initial and final concentration and volume when solvent is added to a solution.
- Limiting reactant
- Reactant that is fully consumed first; determined by comparing available moles divided by stoichiometric coefficients.
- Percent yield
- Actual yield divided by theoretical yield times 100; theoretical yield comes from the limiting reactant calculation.
- Ideal gas law
- PV = nRT with R = 0.0821 L·atm/(mol·K); temperature must be expressed in kelvin.
- Dalton's law
- Total pressure of a gas mixture equals the sum of the partial pressures of the individual gases present.
- Calorimetry equation
- q = mcΔT gives heat transferred; c is specific heat capacity and ΔT is the temperature change in kelvin or Celsius.
- Hess's law
- Enthalpy change of an overall reaction equals the sum of enthalpy changes of its steps, regardless of pathway.
- Gibbs free energy
- ΔG = ΔH - TΔS; a negative value indicates a spontaneous process at constant temperature and pressure.
- Le Chatelier's principle
- A system at equilibrium shifts to offset a stress such as concentration, pressure, or temperature change.
- Equilibrium constant K
- Ratio of product concentrations to reactant concentrations raised to coefficients; changes only with temperature.
- pH definition
- pH = -log[H3O+]; pH plus pOH equals 14 at 25 degrees Celsius because Kw is 1.0×10^-14.
- Buffer
- Solution of a weak acid and its conjugate base that resists pH change; capacity is greatest near pH = pKa.
- Oxidation
- Loss of electrons by a species; occurs at the anode of an electrochemical cell and increases oxidation number.
- Standard cell potential
- E°cell = E°cathode - E°anode; a positive value indicates a spontaneous galvanic reaction.
- VSEPR theory
- Electron domains repel and arrange to minimize repulsion; four domains give tetrahedral geometry with 109.5° angles.
- Hybridization
- Mixing of atomic orbitals; steric number 2 gives sp, 3 gives sp2, and 4 gives sp3 hybridization.
- Hydrogen bonding
- Strong dipole attraction when hydrogen is bonded to N, O, or F; explains water's high boiling point.
- Empirical formula
- Simplest whole-number ratio of atoms in a compound; derived by dividing moles by the smallest mole value.
- Solubility rules
- Most nitrate, sodium, potassium, and ammonium salts dissolve; most chlorides dissolve except those of silver, lead, and mercury.
- Colligative properties
- Properties depending on particle count, not identity; include boiling point elevation and freezing point depression.
- Half-life
- Time for half of a radioactive sample to decay; t1/2 = ln2/k and is independent of initial amount.
- Alpha decay
- Emission of a helium-4 nucleus; mass number decreases by 4 and atomic number decreases by 2.
- Beer-Lambert law
- A = εbc; absorbance is proportional to concentration and path length, enabling colorimetric concentration determination.
- Significant figures
- Digits expressing measurement precision; multiplication uses least sig figs, addition uses least decimal places.
- Precision versus accuracy
- Precision is repeatability among measurements; accuracy is closeness to the accepted or true value.
- GHS pictograms
- Symbols on labels and safety data sheets communicating hazards such as flammability, corrosivity, toxicity, and reactivity.
- Rate law
- Equation relating reaction rate to reactant concentrations; exponents are determined experimentally, not from coefficients.