WACE Chemistry ATAR flashcards
WACE Chemistry ATAR · 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 defines the element and equals the number of electrons in a neutral atom.
- Isotopes
- Atoms of the same element with identical proton numbers but different neutron numbers, so they have different mass numbers but similar chemical properties.
- First ionisation energy
- The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions.
- Electronegativity
- A measure of the tendency of an atom in a bond to attract shared electrons toward itself. It increases across a period and decreases down a group.
- VSEPR theory
- A model predicting molecular shape: electron domains around a central atom repel each other and arrange to maximise separation, with lone pairs repelling more strongly than bonding pairs.
- Hydrogen bonding
- A strong dipole-dipole attraction between a hydrogen atom bonded to N, O or F and a lone pair on a nearby electronegative atom, raising melting and boiling points.
- Ionic lattice energy
- The energy released when gaseous ions form a solid ionic lattice. It increases with higher ionic charges and smaller ionic radii.
- Molar mass
- The mass of one mole of a substance in grams per mole, numerically equal to the relative molecular mass from the periodic table.
- Limiting reagent
- The reactant that is completely consumed first, determined by dividing each amount by its stoichiometric coefficient; it sets the maximum product yield.
- Percentage yield
- The actual mass or moles of product obtained divided by the theoretical maximum, multiplied by one hundred to express it as a percentage.
- Empirical formula
- The simplest whole-number ratio of atoms of each element in a compound, found by dividing mole amounts by the smallest value.
- Molar volume of gas
- The volume occupied by one mole of any gas under specified conditions, approximately 24.79 litres per mole at standard conditions.
- Brønsted-Lowry acid
- A proton donor. It releases a hydrogen ion, and its conjugate base is the species remaining after the proton is lost.
- pH definition
- The negative base-ten logarithm of the hydrogen ion concentration in mol per litre; a lower pH indicates a more acidic solution.
- Buffer solution
- A solution of a weak acid and its conjugate base that resists pH change when small amounts of strong acid or base are added.
- Equivalence point
- The point in a titration where the acid and base have reacted in exactly their stoichiometric mole ratio, determined by the indicator colour change.
- Oxidation
- The loss of electrons by a species, accompanied by an increase in oxidation number. The species oxidised acts as the reducing agent.
- Oxidation number
- A number assigned to an atom showing its electron loss or gain relative to the free element, used to identify redox changes.
- Standard cell potential
- The electromotive force of a galvanic cell under standard conditions, calculated as the cathode reduction potential minus the anode reduction potential.
- Faraday constant
- The charge carried by one mole of electrons, approximately 96 485 coulombs per mole, used to relate current and time to moles reacted.
- Enthalpy change
- The heat energy transferred at constant pressure during a reaction, negative for exothermic reactions and positive for endothermic reactions.
- Hess's law
- The total enthalpy change of a reaction is independent of the pathway, allowing unknown enthalpy changes to be calculated by combining known equations.
- Bond enthalpy
- The energy required to break one mole of a particular bond in the gaseous state; reaction enthalpy equals bonds broken minus bonds formed.
- Activation energy
- The minimum energy colliding particles must possess for a reaction to occur; catalysts lower it by providing an alternative pathway.
- Dynamic equilibrium
- A state in a closed system where forward and reverse reaction rates are equal, so concentrations remain constant although both reactions continue.
- Le Chatelier's principle
- When a system at equilibrium is disturbed by a change in concentration, pressure or temperature, the position of equilibrium shifts to oppose that change.
- Equilibrium constant Kc
- The ratio of product concentrations to reactant concentrations, each raised to its stoichiometric coefficient, at equilibrium; it varies only with temperature.
- Homologous series
- A family of organic compounds with the same functional group and general formula, whose successive members differ by one CH2 unit.
- Esterification
- A reversible reaction between a carboxylic acid and an alcohol, catalysed by concentrated acid, producing an ester and water.
- Structural isomers
- Compounds with the same molecular formula but different arrangements of atoms, giving different physical and chemical properties.
- Flame test
- A qualitative test where a metal ion in a flame emits characteristic light, identifying the metal by the colour observed.
- Chromatography Rf value
- The distance travelled by a solute divided by the distance travelled by the solvent front, used to identify substances under fixed conditions.