TASC Chemistry Level 4 flashcards
TASC Chemistry Level 4 · 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
- The number of protons in the nucleus of an atom; it determines the element's identity and equals the electron count in a neutral atom.
- Mole
- The SI unit of amount of substance: 6.022 × 10²³ particles (Avogadro's number). One mole of a substance has a mass in grams equal to its molar mass.
- Molar mass
- The mass of one mole of a substance in grams per mole, calculated by adding the atomic masses of all atoms shown in its chemical formula.
- Ionic bond
- The electrostatic attraction between oppositely charged ions, usually formed when a metal transfers electrons to a nonmetal, producing a crystalline solid.
- Covalent bond
- A chemical bond in which two atoms share one or more pairs of valence electrons; it typically forms between nonmetals and may be polar or nonpolar.
- pH scale
- A logarithmic scale of acidity: pH = −log[H₃O⁺]. Values below 7 are acidic, 7 is neutral, and above 7 are basic at 25 °C.
- Le Chatelier's principle
- If a system at equilibrium is disturbed by a change in concentration, pressure, or temperature, it shifts in the direction that partially offsets that change.
- Oxidation
- The loss of electrons by a species, accompanied by an increase in oxidation number; it always occurs together with reduction in a redox reaction.
- Independent variable
- The factor that the experimenter deliberately changes or manipulates in an investigation; it is plotted on the x-axis of a graph.
- Dependent variable
- The factor that is measured or observed in an experiment and is expected to respond to changes in the independent variable; plotted on the y-axis.
- Control group
- The group in an experiment that receives no treatment or a placebo; its results provide the baseline for judging the effect of the treatment.
- Accuracy
- How close a measured value is to the true or accepted value; accuracy is commonly quantified with percent error.
- Precision
- How close repeated measurements are to one another under the same conditions; precise data can still be inaccurate if a systematic error exists.
- Significant figures
- The digits in a measurement that carry meaning for its precision: all certain digits plus one estimated digit, excluding leading zeros.
- Percent yield
- The actual mass of product obtained divided by the theoretical maximum mass predicted by stoichiometry, multiplied by 100.
- Titration
- A procedure in which a solution of known concentration is added from a burette until the indicator changes color, allowing calculation of an unknown concentration.
- IUPAC naming
- Systematic rules for naming compounds: choose the longest carbon chain, number to give the lowest locants, and use -ane, -ene, or -yne suffixes.
- State symbols
- Parenthetical labels in a chemical equation showing physical state: (s) solid, (l) liquid, (g) gas, and (aq) dissolved in water.
- Net ionic equation
- An equation showing only the ions and molecules that actually change during a reaction, with spectator ions cancelled from both sides.
- Scientific notation
- A way of writing numbers as a coefficient between 1 and 10 multiplied by a power of ten, useful for very large or very small values.
- Structural formula
- A representation showing which atoms are bonded to which, using lines for bonds; it reveals connectivity that a simple molecular formula does not.
- Spectator ion
- An ion that appears on both sides of a complete ionic equation unchanged and therefore does not participate in the reaction itself.
- Graph axis convention
- By convention the independent variable goes on the x-axis and the dependent variable on the y-axis, each labeled with quantity and unit.
- Line of best fit
- A straight line drawn through a scatter plot that best represents the trend of the data, used to interpolate and extrapolate values.
- Greenhouse gas
- An atmospheric gas such as CO₂, CH₄, or N₂O that absorbs infrared radiation emitted by Earth, warming the lower atmosphere.
- Catalytic converter
- A device in vehicle exhaust systems that uses platinum, palladium, and rhodium catalysts to convert CO, hydrocarbons, and NOₓ into less harmful gases.
- Complete combustion
- The reaction of a fuel with sufficient oxygen to produce only carbon dioxide and water, releasing the maximum amount of energy.
- Hard water
- Water containing high concentrations of dissolved calcium and magnesium ions, which form scale and reduce the lathering of soap.
- Acid rain
- Precipitation with a pH below about 5.6, formed when sulfur dioxide and nitrogen oxides react with water and oxygen in the atmosphere.
- Galvanic cell
- An electrochemical cell that produces electrical energy from a spontaneous redox reaction, with oxidation at the anode and reduction at the cathode.
- Aluminum recycling
- Reprocessing scrap aluminum into new products; it requires only about five percent of the energy needed to smelt the metal from ore.
- Water treatment
- A sequence of processes such as coagulation, sedimentation, filtration, and disinfection that removes suspended solids and pathogens from drinking water.