AS CIE Chemistry Practice Flashcards

Comprehensive vocabulary-style flashcards covering definitions, bonding, energetics, kinetics, and organic chemistry concepts for AS Level Chemistry.

unified atomic mass unit

one twelfth the mass of a carbon-12 atom

Relative isotopic mass

The mass of a particular atom of an isotope compared to the unified atomic mass unit

Relative atomic mass ($A_r$)

The weighted average mass of an atom in a given sample of element compared to the unified atomic mass unit

Relative molecular mass ($M_r$)

The weighted average mass of a molecule compared to the value of the unified atomic mass unit

Relative formula mass

The weighted average mass of a formula unit compared to the unified atomic mass unit

mole

The measure of the amount of particles (eg atoms, ions & molecules) in a substance; the amount of a substance that contains as many particles as there are atoms in exactly $12\,g$ of carbon-12

empirical formula

The simplest formula which shows the whole number ratio of the elements in one molecule or formula unit of the compound.

molecular formula

Actual number of each element present in a molecule of a compound

limiting reactant

the reactant that is not in excess and is used up completely in the reaction.

isotopes

Different atoms of the same element with the same number of protons but different number of neutrons.

Ionisation energy

The energy required to remove a mole of electrons from a mole of gaseous atoms or ions to form one mole of gaseous ions.

first ionization energy

The energy required to remove a mole of electrons from a mole of gaseous atoms to form one mole of gaseous $1^{+}$ ions.

shell

A group of orbitals that are about the same distance from the nucleus.

Subshell

A group of orbitals with the same energy level but with different orientation in space.

Orbital

A region of space around the nucleus where an electron is likely to be found.

Electronegativity

the power of an atom that is covalently bonded to another atom to attract bonding electrons to itself.

Ionic bonding

The electrostatic attraction between oppositely charged ions

metallic bonding

The electrostatic attraction between positive metal ions and delocalised electrons.

covalent bonding

The electrostatic attraction between the nuclei of two atoms and a shared pair of electrons.

dative covalent bonding

a covalent bond in which both electrons in the bond are provided by one species

bond energy

Energy required to break one mole of a particular covalent bond in the gaseous state.

bond length

Internuclear distance of two covalently bonded atoms.

Standard conditions

$100\,kPa$ and $298\,K$

Standard Enthalpy Change of Reaction

The enthalpy change when the amounts of reactants shown in the equation react to give products under standard conditions, with reactants and products in their standard states.

standard enthalpy change of formation

the enthalpy change when $1\,mole$ of a compound is formed from its elements in their standard states under standard conditions.

Standard enthalpy change of combustion

The enthalpy change when one mole of a substance is burnt in excess oxygen, under standard conditions

Standard enthalpy change of solution

The enthalpy change when one mole of solute/substance is dissolved in a solvent to form an infinitely dilute solution under standard conditions.

Standard enthalpy change of neutralization

the enthalpy change when one mole of water is formed when an acid reacts with an alkali under standard conditions.

Standard enthalpy change of atomization

The enthalpy change when one mole of gaseous atoms is formed from its element under standard conditions

Standard enthalpy change of hydration

The enthalpy change when $1\,mole$ of gaseous ions is dissolved in a large amount of water under standard conditions.

lattice energy

the enthalpy change when $1\,mole$ of an ionic compound is formed from its gaseous ions under standard conditions

Hess's Law

states that "the total enthalpy change in a chemical reaction is independent of the route by which the chemical reaction takes place as long as the initial and final conditions are the same"

Le Chatelier's Principle

If a change is made to a system at dynamic equilibrium, the position of equilibrium moves to minimise this change.

mole fraction

the ratio of moles of a particular gas to the total number of moles of gas present

strong acid

an acid that (almost) completely dissociates in aqueous solutions and is a proton donor

weak acid

acid that partially dissociates in aqueous solutions and is a proton donor

Amphoteric

a substance that can act as both an acid and a base (e.g. $Al_2O_3$)

rate of reaction

the speed at which a chemical reaction takes place; concentration/time

activation energy ($E_A$)

the minimum energy required for a collision to be effective.

catalyst

a substance that increases the rate of a reaction but remains chemically unchanged itself at the end of the reaction

hydrocarbon

a compound made up of $C$ and $H$ atoms only

Homologous series

A series of organic compounds having the same functional group and in which one member differs from the next by $-CH_2$.

Homolytic fission

Breaking of a covalent bond such that one electron goes to each of the atoms, forming free-radicals

Heterolytic fission

Breaking of a covalent bond such that both the electrons go to the same atom, forming positive and negative ions.

Free-radical

an atom or group of atoms with an unpaired electron formed from the homolytic fission of a covalent bond.

Nucleophile

A species that contains a lone pair of electrons (electron pair donor) and is attracted to parts of molecules which are electron-deficient.

Electrophile

electron deficient species (electron pair acceptor) which can accept electrons and is attracted to parts of molecules which are electron rich.

structural isomerism

Isomers that have the same molecule formula but different structural formulae

stereoisomerism

compounds whose molecules have the same atoms bonded to each other but with different arrangements of the atoms in space.

chiral center

a carbon atom with four different atoms or groups of atoms bonded to it.

polymer

long-chain molecule that is made up of many repeating subunits (monomers)

pi bond ($\pi$)

multiple covalent bonds involving the sideways overlap of p atomic orbitals

sigma bond

single covalent bonds formed by end-to-end overlap

Ideal Gas Law

$$PV = nRT$$

oxidation

loss of electrons, addition of oxygen, removal of hydrogen, or an increase in oxidation number

reduction

gain of electrons, loss of oxygen, addition of hydrogen, or a decrease in oxidation number

oxidising agent

a substance which gets reduced (gains electrons/electron acceptor) and increases the oxidation number of another atom

reducing agent

the substance that gets oxidised (loses electrons/electron donor) and decreases the oxidation number of another atom

Atomic radius

half the distance between two nuclei of covalently bonded atoms of the same element

Coordination number

the number of atoms or ions immediately surrounding a central atom in a complex or crystal.

Photochemical smog

the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere to form secondary pollutants

Vapour pressure

The pressure created by the vapour evaporating from a liquid; gas particles hitting the walls of the container

dynamic equilibrium

When the rate of the forward reaction is equal to the rate of the reverse reaction and concentrations of reactants and products remain unchanged.