A Level Chemistry Definitions Flashcards
Isotopes
Atoms of the same element with different numbers of neutrons and different mass numbers.
Relative Isotopic Mass
The mass of an isotope compared with 1/12 of the mass of an atom of carbon-12.
Relative Atomic Mass
The weighted mean mass of an atom compared with 1/12 of the mass of an atom of carbon-12.
Mole
The amount of substance that contains 6.02 x 10^23 (Avogadro’s number) particles.
Empirical Formula
The simplest whole number ratio of atoms of each element present in a compound.
Molecular Formula
The number and type of atoms of each element present in a molecule.
Anhydrous
A compound that doesn’t contain any water of crystallisation.
Hydrated
A compound that contains water(s) of crystallisation.
Water Of Crystallisation
Water molecules that form an essential part of a compound’s crystalline structure.
Acid
A substance that releases H+ ions in aqueous solution.
Alkali
A substance that releases OH- ions in aqueous solution.
Weak Acid
An acid that partially dissociates in solution.
Strong Acid
An acid that fully dissociates in solution.
Orbital
A region around the nucleus that can hold up to 2 electrons in opposite spin.
Ionic Bonding
Electrostatic attraction between oppositely charged ions.
Covalent Bonding
Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
Dative Bond
A covalent bond where both of the shared electrons are donated by one of the bonding atoms.
Electronegativity
The ability of an atom to attract a shared pair of electrons in a covalent bond.
Periodicity
Repeating trends in physical/chemical properties across periods of the periodic table.
First Ionisation Energy
The amount of energy required to remove one mole of electrons from one mole of gaseous atoms in order to form one mole of gaseous 1+ ions.
Metallic Bonding
Electrostatic attraction between metal cations and delocalised electrons.
Disproportionation
Oxidation and reduction of the same element in a reaction.