Definitions 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 groups of ions
Molar mass
The mass of one mole of a substance
Anhydrous
A salt which contains no water of crytallisation
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 an atom
Mass number
The total number of protons and neutrons in an atom
Relative atomic mass
The average mass of an atom of an element relative to one-twelfth the mass of an atom of carbon-12
Relative isotopic mass
The mass of an atom of an isotope of an element relative to one-twelfth the mass of an atom of carbon-12
Isotopes
Atoms that have the same atomic number but a different mass number
Relative Formula Mass
The average mass of a formula unit relative to one-twelfth the mass of an atom of carbon-12
Relative molecular mass
The average mass of a molecule relative to one-twelfth 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 one mole of gaseous ions with a triple positive charge
Covalent bond
The electrostatic attraction between a shared pair electrons and the nuclei of bonded atoms
Co-ordinate 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 eight 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
The attraction between the positive end, 𝞭+, of the permanent dipole on a molecule and the negative end, 𝞭-, of the permanent dipole on a neighbouring molecule.
Hydrogen bond
The attraction between a lone pair of electrons on a very electronegative atom (N, O or F) in one molecule and a hydrogen atom of a neighbouring molecule, in which the hydrogen atom is covalently bonded to a very electronegative atom (N,O or F)
Redox
Oxidation and reduction occur in the same reaction
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 moldm-3, expressed as M
Standard solution
A solution of known concentration
