Chemistry Module 2 - Terms

Definition of isotopes,atoms of the same element with different number of neutrons and different masses

Definition of relative atomic mass,The weighted mean mass of an atom of an element relative to 1/12th of the mass of a C-12 atom

Definition of relative isotopic mass,The mass of one atom of an isotope compared to the 1/12 of the mass of a carbon-12 atom

Definition of the mole,the amount of a substance that contains 6.02x10^23 particles

Definition of avagadro constant,the number of particles in each mole of substance

Definition of molecular formula,The number of atoms of each element in a molecule

Definition of empirical formula,The simplest whole number ratio of atoms of each element in a compound

Definition of hydrated,A crystalline compound that contains water

Definition of water of crystallisation,Water molecules that form part of the crystalline structure of a compound.

Definition of anhydrous,A crystalline compound containing no water

Definition of theoretical yield,The maximum possible amount of a product.

Definition of atom economy,A measure of the amount os starting material that end up as useful product.

Definition of concentration,The amount of solute (in mol) dissolved in each 1dm^3 of solution

Definition of molar gas volume,The volume that a mole of gas occupies at a certain temperature and pressure
(room temperature and pressure 20 degrees celcius and 101kpa, 1 mol of gas = 24dm^3

Definition of acid,proton donor

Definition of base,proton acceptor

Definition of alkali,base which dissolves in water to release hydroxide ions

Definition of salt,a chemical compound formed from an acid when the H+ ion from the acid is replace by a metal ion or NH4+

Definition of reduction,gain of electrons, loss of oxygen

Definition of oxidation,Loss of electrons, gain of oxygen

Definition of oxidation number,the number of electrons that an atoms uses to bond with atoms of another element (e- lost or gained,)

Definition of Oxidising Agent,Substance that oxidises another species and is itself reduced in the process

Definition of Reducing Agent,Substance that reduces another species and is itself oxidised in the process

Definition of Atomic Orbital,A region of space that can hold up to 2 electrons with opposite spin

Definition of electronic configuration,The number of electrons that an atom/ion has and how they are arranged

Definition of ionic bonding,The electrostatic attraction between oppositely charged ions

Definition of covalent bonding,The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Definition of dative covalent bond,when both bonding electrons in the shared pair come from 1 atom.

Definition of electron pair repulsion theory,electron pairs repel as far apart as possible and lone pairs repel more than bonding pairs

Definition of electronegativity,the ability of an atom to attract electrons pair to itself in a chemical bond

Definition of a pure covalent bond,When two atoms in a covalent bond have the same electronegativity. Electron charge is evenly distributed and there is no permanent dipole across the bond - non polar molecule.

Definition of a polar covalent bond,When two atoms in a covalent bond have different electronegativities, the electrons are pulled towards the more electronegative atom, forming a permanent dipole and a polar bond

Definition of dipole,An uneven distribution of charge ( electron density.)

Definition of intermolecular forces,Weak forces between molecules / dipole.