Definitions Flashcards
Define an isotope
atoms which have the same number of protons but different numbers of neutrons
Define relative isotopic mass
The mass of an atom of the isotope compared with 1/12th of the mass of an atom of carbon-12
Define relative atomic mass
The weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12
Define relative molecular mass
The weighted mean mass of a molecule of that substance compared to 1/12th of the mass of an atom of carbon-12
Define relative formula mass
The average mass of a formula unit of that substance compared to 1/12th of the mass of an atom of carbon-12
Define a mole
The amount of substance that contains 6.02 x 10^23 particles
Define molar mass
The mass (in grams) of 1 mole of a substance. The units of molar mass are g mol ^-1
Define an orbital
A region of space that can hold up to 2 electrons, with opposite spins
Define an ion
An atom or group of atoms that has lost or gained one or more electrons
Define molecular formula
Shows the number of atoms of each element in one molecule of the substance
Define empirical formula
Shows the simplest whole number ratio of atoms of each element present in a substance
Define an acid
A compound that releases H+ ions in aqueous solution
Define a base
A compound that neutralises an acid to form a salt
Define an alkali
A type of base that dissolves in water to release hydroxide ions, OH-
Define a salt
A compound formed when the H+ ion from an acid is replaced by a metal ion or an ammonium ion
Define ionic bonding
The electrostatic attraction between positive and negative ions
Define a giant ionic lattice
A regular array of alternating positive and negative ions
Define a covalent bond
The attraction of a shared pair of electrons for the nuclei of the bonded atoms
Define a dative covalent bond
One in which both of the electrons in the covalent bond are provided by the same atom
What does the electron pair repulsion theory state
That the electron pairs in the outer shell of the central atom in a molecule repel each other and therefore arrange themselves to be as far away from each other as possible
Define electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond
Define induced dipole-dipole forces
Attractive forces between molecules that arise when random electron movements in one molecule cause an instantaneous dipole which in turn causes an induced dipole in the other molecule
Define permanent dipole-dipole forces
Electrostatic attraction forces between polar molecules. The positive pole of one molecule is attracted to the negative pole of a neighbouring molecule
Define a hydrogen bond
The intermolecular attraction between hydrogen covalently bonded to N, O, or F of one molecule and the LONE PAIR on N,O, or F in another molecule
Define metallic bonding
The attraction between a lattice of positive ions and a sea of delocalised electrons
Define oxidation
Loss of electrons or an increase in oxidation number
Define reduction
Gain of electrons or a decrease in oxidation number
Define oxidising agent
The substance that contains the element that is reduced
Define reducing agent
The substance that contains the element that is oxidised
Define functional group
An atom or group of atoms that gives a compound its characteristics chemical reactivity
Define homologous series
A series of compounds that have the same functional group and the same general formula, and in which successive members of the series differ by an extra CH2 unit
Define hydrocarbons
Compounds which contain only carbon and hydrogen
Define saturated
Compounds which contain single bonds between carbon atoms
Define isomer
Different compounds that have the same molecular formula
Define structural isomers
Compounds that have the same molecular formula but different structural formula
Define a radical
An atom or group of atoms which has an unpaired electron
Define homolytic fission
The breaking of a covalent bond with one of the bonded electrons going to each atom, forming 2 radicals
Define heterolytic fission
The breaking of a covalent bond forming a cation and an anion
Define stereoisomers
Compounds with the same structural formula but with a different arrangement in space
Define an electrophile
An electron pair acceptor
What is meant by the term standard solution
A solution of known concentration
