CCEA Definitions AS1 Flashcards
Molecular ion
Two or more atoms covalently bonded with an overall charge
Avogadro’s Constant
Number of atoms in 12.000g of carbon-12
Mole
The amount of substance which contains the Avogadro constant of atoms, molecules, or group of ions.
Molar mass
The mass of one mole of a substance.
Anhydrous
A salt which contains no water of crystallisation.
Hydrated
A salt which contains water of crystallisation.
Water of crystallisation
Water chemically bonded within a crystal structure.
Atomic Number
The number of protons in the nucleus of an atom.
Mass number
The total number of protons and neutrons in the nucleus of an atom.
Relative Atomic Mass (RAM)
The average mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.
Relative Isotopic Mass (RIM)
The mass of an atom of an isotope of an element relative to 1/12th of the mass of an atom of carbon-12.
Isotopes
Atoms which have the same atomic number but a different mass number.
Relative Formula Mass (RFM)
The average mass of a formula unit relative to 1/12th of the mass of an atom of carbon-12.
Relative Molecular Mass (RMM)
The average mass of a molecule relative to 1/12th of the mass of an atom of carbon-12.
First Ionisation Energy
The energy required to convert one mole of gaseous atoms into gaseous ions with a single positive charge.
Second Ionisation Energy
The energy required to convert one mole of gaseous ions with a single positive charge into gaseous ions with a double positive charge.
Third Ionisation Energy
The energy required to convert one mole of gaseous ions with a double positive charge into gaseous ions with a triple positive charge.
Covalent Bond
The electrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms.
Dative Bond
A shared pair of electrons between two atoms - One atom provides both electrons.
Octet Rule
When reacting, an atom tends to gain, lose, or share electrons to achieve 8 in its outer shell.
Electronegativity
The extent to which an atom attracts the bonding electrons in a covalent bond.
Polar bond
A covalent bond in which there is unequal sharing of the bonding electrons.
Delocalised electrons
Outer electrons do not have fixed positions but move freely.
Intermolecular
Between neighbouring molecules.
van der Waals’ Forces
The attraction between instantaneous and induced dipoles on neighbouring molecules.
Permanent dipole-dipole attraction
Attraction between the positive end of the permanent dipole on a molecule with the negative end of the permanent dipole of a neighbouring molecule.
Hydrogen bond
The attraction between a lone pair of electrons on a very electronegative atom (N,O,F) in one molecule and a hydrogen atom in a neighbouring molecule, in which the hydrogen atom is covalently bonded to a very electronegative atom (N,O,F).
Redox
Oxidation and reduction occur in the same reaction at the same time.
Oxidation
Loss of electrons/increase in oxidation state.
Reduction
Gain of electrons/decrease in oxidation state.
Oxidising agent
electron acceptor
Reducing agent
Electron donor
Disproportionation
Oxidation and reduction of the same element in the same reaction.
Strong acid/base
Fully dissociates in solution
Weak acid/base
Partially dissociates in solution
Molarity
Concentration in mol dm-3 expressed using M.
Concentration
Number of moles present in a stated volume.
Standard solution
A solution for which the concentration is known.
Ionic Bonding
The electrostatic attraction between oppositely charged ions formed by electron transfer.
Orbital
A region within an atom that can hold up to two electrons with opposite spins.
Lone pair
A pair of unshared electrons in the outer shell of an atom.
