A2 Paper 1 Definitions (M3 & M5) Flashcards
What is Periodicity?
The repeating trends in physical and chemical properties
Elements are arranged by increasing atomic (proton) number and in groups with similar chemical properties.
Why is Mg classed as a s-block element?
S-block element has its highest energy electron in a s subshell
This classification helps in understanding the electron configuration of elements.
What is First Ionisation Energy?
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
What is Second Ionisation Energy?
The energy required to remove one electron from each 1+ ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions
Define Successive Ionisation Energy.
A measure of the energy required to remove each electron in turn
Define Metallic Bonding.
Strong electrostatic attraction between positively charged ions (cations) and delocalised electrons
What is Disproportionation?
The simultaneous oxidation and reduction of the same element in the same redox reaction
Define an Exothermic Reaction.
A reaction where heat energy is released to the surroundings (ΔH is negative)
What is an Endothermic Reaction?
A reaction where heat energy is absorbed from the surroundings (ΔH is positive)
What is average bond enthalpy, ΔEHϑ?
The average enthalpy change for the breaking of 1 mole of bonds in gaseous molecules.
What are standard conditions?
Temperature = 25°C (298K), Pressure = 1 atm (100 kPa), and all solutions must have a concentration = 1.00 mol dm-3.
What is the standard enthalpy change of formation, ΔfHϑ?
The enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions.
What is the standard enthalpy change of combustion, ΔcHϑ?
The enthalpy change for complete combustion of one mole of a substance under standard conditions, all reactants and products being in their standard states.
What is the standard enthalpy change of neutralisation, ΔneutHϑ?
The enthalpy change that accompanies the formation of one mole of H2O(l) from neutralisation, under standard conditions.
What is the rate of reaction?
The change in concentration of a reactant or a product per unit time.
Rate = Concentration of reactant (or product) mol dm-3; UNITS = mol dm-3 s-1
What is activation energy?
The minimum energy required to start a reaction by breaking bonds.
What is homogeneous catalysis?
Catalysis of a reaction in which the catalyst and the reactants are in the same physical state.
What is heterogeneous catalysis?
Catalysis of a reaction in which the catalyst has a different physical state from the reactants.
What is dynamic equilibrium?
- Exists in a closed system
- when the rate of the forward reaction is equal to the rate of the reverse reaction
- and the concentrations of reactants and products do not change.
What is Le Chatelier’s principle?
When a system in dynamic equilibrium is subjected to change, the equilibrium position will shift to minimise the change.
What is the Kc expression for the reaction H2 + I2 ↔ 2HI?
Kc = [HI]² / [H2] [I2]
What is Rate-determining step?
The slowest step in a multi-step reaction
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What is half-life of a reactant, t1/2?
Time taken for the concentration of the reactant to reduce by half
What is the arrhenius equation (in the equation of a straight line form)?
What is Mole fraction x(A)?
Number of moles of A / total number of moles in a gas mixture
Define Partial Pressure p(A).
Mole fraction of A x total pressure P
What does enthalpy change of atomisation, ΔatHϑ represent?
The enthalpy change when one mole of gaseous atoms is formed from its element, under standard conditions
Define first electron affinity, ΔEA1Hϑ.
The enthalpy change when one electron is added to each atom in one mole of gaseous atoms, to form one mole of gaseous 1- ions
What is second electron affinity, ΔEA2Hϑ?
The enthalpy change when one electron is added to each ion in one mole of gaseous 1- ions, to form one mole of gaseous 2- ions
Define Lattice Enthalpy, ΔLEHϑ.
Enthalpy change when one mole of an ionic compound is formed from its gaseous ions
What is Standard Enthalpy Change of Solution, ΔsolHϑ
Enthalpy change that takes place when one mole of compound (solute) is completely dissolved in water under standard conditions
What is Standard Enthalpy Change of Hydration, ΔhydHϑ?
The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions
This process is critical in understanding ion solvation.
What does Entropy, S measure?
A measure of the dispersal of energy in a system, greater when the system is more disordered
What is standard entropy change of reaction, ΔSϑ?
The entropy change that accompanies a reaction in molar quantities expressed in a chemical equation under standard conditions
What is Gibbs’ Equation?
ΔG = ΔH – TΔS
When is a reaction classed as being feasible according to Gibbs’ Equation?
When ΔG is negative
What is a BrØnsted-Lowry Acid?
A proton (H+) donor
Define BrØnsted-Lowry Base.
A proton (H+) acceptor
What is a Strong Acid?
Completely dissociates into its ions in solution to donate a proton
What is a Weak Acid?
Partially dissociates into its ions in solution to donate a proton
What is a salt?
Is produced when a H+ ion from an acid is replaced by a metal ion or an ammonium ion (NH4)
Define the term conjugate acid-base pair.
A pair of two species that transform into each other by the gain or loss of a proton (H+)
What is the formula for pH?
pH = -log[H+]
How to calculate H+?
H+ = 10-pH
Calculate pKa.
pKa = -log[Ka]
Calculate Ka.
Ka = 10-pKa
Calculate Kw.
[H+][OH-]
What is a Buffer Solution?
A mixture that minimises pH change on addition of small amounts of acid or base
What does standard electrode (redox) potential, Eθ measure?
The e.m.f. of a half-cell compared with a standard hydrogen half-cell, measured at 298K with solution concentrations of 1 mol dm-3
What is a Transition Element.
A d-block element that forms an ion with an incomplete d sub-shell
What is a complex ion?
A transition metal ion bonded to one or more ligands by coordinate bonds
Define Ligand.
A molecule or ion that can donate a pair of electrons to the transition metal ion to form a coordinate bond
What is a coordinate bond?
Shared pair of electrons in which one of the bonded atoms provides both electrons for the shared pair
What is coordination number?
The total number of coordinate bonds formed between a central metal ion and its ligands
Define monodentate ligand.
A molecule or ion that can donate one pair of electrons to the transition metal ion to form one coordinate bond. Examples:
What is a bidentate ligand?
Donates two lone pairs of electrons to the central metal ion to form two coordinate bonds. Examples:
What is a multidentate ligand?
Donates more than one lone pair of electrons to the central metal ion to form more than one coordinate bond.
What is an optical isomer.
Stereoisomers that are a pair of non-superimposable mirror images of each other.
