Definitions Flashcards
Define covalent bond.
The electrostatic attraction between a shared pair of electrons and the nuclei of two bonded atoms.
Define lone pair.
A pair of unshared electrons in the outer shell of an atom.
Define coordinate (Dative) bond.
A shared pair of electrons between two atoms with both electrons shared by one atom.
Define octet rule.
When forming a compound, an atom tends to gain, lose or share electrons to achieve eight in its outer shell.
Define electronegativity.
The extent to which an atom attracts the bonding electrons in a covalent bond.
Define Polar bond.
A covalent bond in which there is unequal sharing of the bonding electrons.
Define delocalised electrons.
Outer electrons do not have fixed positions but move freely.
Disproportionation
Oxidation and reduction in he same species in the same reaction.
Avogadro’s number.
Number of atoms in 12.000g of carbon 12.
Mole
The amount of substance which contains the Avogadro number 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 crystallisation.
Hydrated.
A salt which contains water of crystallisation
Water of crystallisation.
Water chemically bonded within a crystal structure.
Intermolecular
Between neighbouring molecules.
Van der Waals forces
The attraction between instantaneous and induced dipoles of neighbouring molecules.
Permanent dipole dipole attraction.
Attraction between the positive end, +, of the permenant dipole on a molecule with a permanent negative dipole, of a neighbouring molecule.
Hydrogen bond
The attraction between a lone pair of electrons on a very electronegative molecules (N, O, F) on one molecule and a hydrogen on a neighbouring molecule, in which the hydrogen is covalently bonded to a very electronegative atom.
Lone pair.
A pair of unshared electrons in the outer shell of an atom.
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.
The average mass of an atom of an element relative to one twelfth of the mass of and atom of carbon 12.
Relative isotopic mass.
The mass of an atom of an isotope of an element relative to one twelfth of the mass of an atom of carbon 12.
Isotopes.
Atoms which have the same atomic number but a different mass number.
Relative molecular mass.
The average mass of a molecule relative to one twelfth of an atom of carbon 12.
Molecular ion.
When there are two or more ions covalently bonded with an overall charge.
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.
Relative formula mass.
The average mass of a formula unit relative to that of one twelfth of carbon 12.
Oxidising agent
Electron acceptor.
Reducing agent.
Electron donor.
Strong acid/base.
An acid/base that fully dissociates in water.
Weak acid/base.
Partially dissociates in water
Oxidation.
Loss of electrons/increase in oxidation state.
Molarity.
Concentration in mol/dm3 expressed using M.
Concentration.
Number of moles or mass present in a stated volume.
Standard solution.
A solution for which the concentration is known.
Orbital
A region within an atom that can hold up to two electrons with opposite spins.
Ionic bonding.
The electrostatic force of attraction between oppositely charged ions formed by electron transfer.
Bond polarity.
Arises when covalently bonded atoms have different have different electronegativity values and partial charges + and - are formed within the bond.
