Ocr A Level Chemistry Already Passed

(successive) ionisation {Ans: A measure of the energy required to remove each electron in turn,}heterolytic fission {Ans: The breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+ ion) and an anion (- ion).}van der Waals' forces {Ans: Very weak attractive forces between induced dipoles in neighbouring molecules.}molecule {Ans: A small group of atoms held together by covalent bonds.}biodegradable material {Ans: A substance that is broken down naturally in the environment by living organisms.}periodicity {Ans: A regular periodic variation of properties of elements with atomic number and position in the Periodic Table.}relative isotopic mass {Ans: The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.}group {Ans: A vertical column in the Periodic Table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons.}hydrocarbon {Ans: A compound of hydrogen and carbon only.}reduction {Ans: Gain of electrons or a decrease in oxidation number.}