Definitions Flashcards
Relative isotopic mass
Mass of a single isotope relative to 1/12th of a C12 atom
Relative atomic mass
The weighted mean mass of an atom of an element relative to 1/12th of a C12 atom.
Metallic bonds
Formed between two metals. Formed between a cloud of free electrons and the positively charged ions.
Atom
The smallest particle of matter and is made up of proton, neutrons and electrons
Molecule
Two or more atoms chemically bonded together
Element
An element is only made up of one sort of atom
Compound
Two or more different types of atom bonded together
Mixture
Two or more different elements and/or compounds in the same space
What is an oxidising agent?
An oxidising agent is a substance that oxidises another atom/ion by causing it to lose electrons (an oxidising agent gets reduced itself)
What is a reducing agent?
A reducing agent is a substance that reduces another atom/ion by causing it to gain electrons (A reducing agent itself gets oxidised)
What is the definition of an ion?
An atom or molecule that has gained or lost its valence electrons.
What is the definition of an isotope?
Atoms of the same element with different numbers of neutrons and different masses.
What is a redox reaction?
A reaction in which both oxidation and reduction takes place
ionic bond
The electrostatic attraction between positive and negative ions
Covalent bond
The electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom.
Empirical formula
The smallest whole number ratio of atoms present in a molecule.
Molecular formula
Number of atoms of each element in a molecule.
Electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond
Dipole
The separation of opposite charges within a molecule
Intermolecular force
Weak interactions between dipoles of different molecules.
Acid
Species that releases H+ ions in aqueous solution. It acts as a proton donor.
Alkali
Type of base that dissolves in water forming OH- ions.
pH
Concentration of H+ ions
Base
A proton acceptor. Substances that can dissolve in water and neutralise acid to produce salt and water.
First ionisation energy
Removal of one mol of electrons from one mol of gaseous atoms to form a positive ion
Second ionisation energy
Energy required to remove one electron from each ion in one mol of gaseous 1+ ions of an element to form one mol of gaseous 2+ ions.
Periodicity
Repeating pattern of properties across a period
Homologous series
A series of organic compounds with the same functional group but with each successive member differing by CH2
Homolytic fission
The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.
Substitution reaction
A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.
Hydrogenation
Addition of hydrogen to an alkene to make an alkane
Addition reaction
Two molecules react together to make on product. The product is saturated
Steam cracking
Long chain hydrocarbons mixed with steam and heated to very high temperatures
Catalytic cracking
Long chain hydrocarbon is heated to high temperature and passed over a catalyst.
E isomer
The groups that are the same are on opposite sides
Z isomer
Groups that are the same are on the same side
Chain isomers
Same molecular formula but different arrangements of the carbon ‘skeleton’
Position isomers
Based on the movement of a functional group in the molecule
functional group isomers
Molecular formula remains the same, but the type of functional group changes
Stereoisomerism
Compounds with same structural formulae but with different arrangements in space
Orbital
Region which can hold up to two electrons
What is a carbocation?
An ion that contains a positively charged carbon atom
What is an electrophile?
An atom which is attracted to an electron rich centre or atom, where it accepts a pair of electrons to form a new covalent bond
Repeat unit
A specific arrangements of atoms that occurs in the structure over and over again
Secondary alcohol
An alcohol in which which the hydroxyl group is attached to a carbon atoms that is attached to two carbon chains and one hydrogen atom
Primary alcohol
An alcohol in which the hydroxyl group is attached to a carbon atom that is tracked to two or three hydrogen atoms
Tertiary alcohols
An alcohol in which the hydroxyl group is attached to a carbon atom that is attached to three carbon atoms and no hydrogen atoms
Activation energy
The minimum energy required to start a reaction by the breaking of bonds
Closed system
A system isolated from its surroundings
Dehydration
An elimination reaction in which water is removed from a saturated molecule to make a unsaturated molecule
Disproportionation
A redox reaction in which the same element is both oxidised and reduced
Endothermic reaction
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings.
Exothermic reaction
A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss.
Fingerprint region
An area of an infrared spectrum below 1500cm^-1 that gives a characteristic pattern for different compounds
Fragmentation
The process in mass spectrometry that causes a positive ion to split into smaller pieces, one of which is a positive fragment ion
Heterogeneous catalyst
A reaction in which the catalyst has a different physical state from the reactants
Homogeneous catalyst
A reaction in which the catalyst has the same physical state as the reactants
Mass number
The sum of the number of protons and neutrons in the nucleus
Proton number (Atomic number)
The number of protons in the nucleus
Reflux
The continual boiling and condensing of a reaction mixture
Repeat unit
A specific arrangement of atoms that occur in the structure over and over again
Standard enthalpy change of combustion
Enthalpy change that takes place when one mole of substance reacts completely with oxygen under standard conditions, all reactants and products in standard states.
Standard enthalpy change of formation
Enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.
Standard enthalpy change of neutralization
Enthalpy change accompanies the reaction of an acid by a base to form one mole of water under standard conditions and standard states.
Strong acid
An acid that dissolves completely in solution
Weak acid
An acid that dissociates only partly in solution
Volatility
The ease at which a liquid turns into a gas (volatility increases as boiling point decreases)
One mole of substance
As many particles as there are carbon atoms in 12g of carbon 12
