A-Level Chemistry Comprehensive Review: Chapters 1-22

Complete set of vocabulary flashcards covering atomic structure, chemical bonding, stoichiometry, energetics, kinetics, equilibria, periodicity, and organic chemistry based on the lecture transcript.

Atomic Number

The number of protons in the nucleus of an atom.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons, resulting in the same atomic number but different mass numbers.

First Ionization Energy (IE)

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous $1+$ ions ($X(g) \rightarrow X^{+}(g) + e^{-}$).

Principal Quantum Number ($n$)

A number that indicates the shell number and relates to the energy and distance of electrons from the nucleus.

Orbitals

Regions of space where there is a high probability of finding electrons, with each orbital holding a maximum of 2 electrons.

Ground State

The lowest energy state of an atom where electrons occupy the lowest available energy levels.

Spin-Pair Repulsion

The phenomenon where electrons in the same orbital repel each other due to their negative charge, making it easier to remove one and slightly reducing ionization energy.

Free Radical

A chemical species with one or more unpaired electrons, making it highly reactive.

Unified Atomic Mass Unit ($U$)

Defined as one twelfth ($1/12$) of the mass of a carbon-12 atom.

Relative Atomic Mass ($A_r$)

The weighted average mass of an atom compared to $1/12th$ of the mass of a carbon-12 atom.

The Mole

The amount of substance that contains as many particles as there are in $12g$ of Carbon-12.

Avogadro's Constant ($N_A$)

The number of particles in one mole, approximately $6.02 \times 10^{23}$.

Empirical Formula

The simplest whole number ratio of atoms of each element in a compound.

Limiting Reagent

The reactant that is completely consumed in a reaction and determines the maximum amount of product formed.

Electronegativity

The ability of an atom to attract bonding electrons towards itself.

Ionic Bonding

The electrostatic attraction between oppositely charged ions (positively charged cations and negatively charged anions).

Metallic Bonding

The electrostatic attraction between positive metal ions and delocalized electrons.

Coordinate Bonding

A type of covalent bond where both electrons in the shared pair are provided by one of the bonding atoms.

Bond Energy

The energy needed to break one mole of a covalent bond in the gas state.

Enthalpy Change ($\triangle H$)

The heat content change during a chemical reaction at constant pressure.

Hess's Law

States that the total enthalpy change during a reaction is the same regardless of whether the reaction occurs in one step or multiple steps.

Oxidation Number

A theoretical charge assigned to an element in a compound that reflects its electron configuration.

Disproportionation

A specific type of redox reaction where a single substance is both oxidized and reduced, resulting in two or more different products.

Dynamic Equilibrium

A state in a closed system where the rate of the forward and reverse reactions are equal, and concentrations of reactants and products remain constant.

Le Chatelier's Principle

States that if a system in equilibrium experiences a change in temperature, concentration, or pressure, the equilibrium shifts to counteract that change.

Brønsted-Lowry Acid

A chemical species that acts as a proton ($H^+$) donor.

Activation Energy ($E_a$)

The minimum energy that reacting particles must have for a collision to be effective and lead to a reaction.

Boltzmann Distribution

A graph showing the distribution of molecular energies in a sample at a given temperature.

Catalyst

A substance that increases the rate of reaction by providing an alternative pathway with lower activation energy without being consumed.

Amphoteric

A substance, such as aluminium oxide ($Al_2O_3$), that can act as both an acid and a base.

Homolytic Fission

The breaking of a covalent bond where the bond breaks evenly, and each atom takes one of the shared electrons to form radicals.

Nucleophile

An electron pair donor, such as $OH^-$ or $NH_3$.

Electrophile

An electron pair acceptor, such as $H^+$ or $Br^+$.

Stereoisomerism

Compounds with the same structural formula but different spatial arrangements, including geometrical (cis/trans) and optical isomers.

Chiral Centre

A carbon atom bonded to four different groups, resulting in non-superimposable mirror images called enantiomers.

Markovnikov's Rule

In electrophilic addition, the major product forms when the hydrogen atom adds to the carbon atom with the most hydrogen atoms already attached, stabilizing the carbocation intermediate.

Molecular Ion Peak ($M^+$)

The peak in a mass spectrum with the highest $m/e$ value, corresponding to the molecular mass of the compound.