JCE Chemistry flashcards
JCE 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.
- Mole
- The amount of substance containing 6.02 × 10²³ particles; calculated as mass in grams divided by molar mass in g/mol.
- Relative atomic mass
- The weighted average mass of the isotopes of an element compared with one-twelfth of the mass of a carbon-12 atom.
- Isotope
- Atoms of the same element with the same number of protons but different numbers of neutrons, giving different mass numbers but identical chemical properties.
- Ionic bond
- The strong electrostatic attraction between oppositely charged ions formed when a metal transfers electrons to a non-metal.
- Covalent bond
- A bond formed when two non-metal atoms share one or more pairs of electrons to achieve full outer shells.
- Giant covalent structure
- A lattice of many atoms joined by covalent bonds, giving very high melting points, as in diamond and silicon dioxide.
- Alloy
- A mixture of a metal with other elements; different-sized atoms disrupt the layers, making the material harder than the pure metal.
- Empirical formula
- The simplest whole-number ratio of atoms of each element in a compound, found by dividing moles by the smallest value.
- Atom economy
- The mass of the desired product divided by the total mass of all reactants, expressed as a percentage of the reaction.
- Percentage yield
- The actual mass of product obtained divided by the theoretical maximum mass, multiplied by 100.
- Neutralisation
- The reaction between an acid and a base producing a salt and water; the H⁺ ions from the acid react with OH⁻ ions.
- Strong acid
- An acid that ionises completely in aqueous solution, releasing all its hydrogen ions, such as hydrochloric and sulfuric acid.
- Titration
- A technique using a burette and pipette to find the exact volume of one solution needed to neutralise a measured volume of another.
- pH scale
- A scale from 0 to 14 measuring acidity: below 7 acidic, 7 neutral, above 7 alkaline, with each unit a tenfold change.
- Activation energy
- The minimum energy that colliding particles must have for a reaction to occur; lowered by a catalyst.
- Collision theory
- The idea that particles must collide with sufficient energy and correct orientation for a successful reaction to take place.
- Catalyst
- A substance that increases reaction rate by providing an alternative pathway with lower activation energy, without being used up.
- Dynamic equilibrium
- The state in a reversible reaction where forward and reverse rates are equal, so concentrations of reactants and products stay constant.
- Exothermic reaction
- A reaction that transfers energy to the surroundings, causing a temperature rise, with a negative enthalpy change.
- Electrolysis
- The breakdown of an ionic compound using a direct current, with cations reduced at the cathode and anions oxidised at the anode.
- Displacement reaction
- A reaction in which a more reactive element takes the place of a less reactive element in its compound or salt solution.
- Reactivity series
- A list of metals ordered by how readily they react, used to predict extraction methods and reactions with acid and water.
- Galvanising
- Coating iron with zinc to prevent rusting; the zinc acts as a barrier and as a sacrificial metal.
- Fractional distillation
- Separation of liquids with different boiling points by repeated vaporisation and condensation on a fractionating column.
- Alkene
- An unsaturated hydrocarbon with a carbon-carbon double bond and general formula CₙH₂ₙ, which decolourises bromine water.
- Homologous series
- A family of compounds with the same general formula and similar chemical properties, differing by CH₂ units.
- Cracking
- The breakdown of large alkane molecules into smaller alkanes and alkenes using heat and a catalyst.
- Chromatography
- A separation technique in which substances move at different rates between a mobile phase and a stationary phase.
- Rf value
- The distance moved by a spot divided by the distance moved by the solvent front in chromatography, used to identify substances.
- Flame test
- A test identifying metal ions by the colour they give in a flame, such as yellow for sodium and lilac for potassium.
- Group 1 trend
- Alkali metal reactivity increases down the group because the outer electron is further from the nucleus and lost more easily.
- Halogen displacement
- A more reactive halogen displaces a less reactive halogen from its salt solution, showing the trend in Group 7 reactivity.