Ocr A Level Chemistry Exam Questions (156 Terms) With Verified Definitions Updated 2024

thermal decomposition {Ans: The breaking up of a chemical substance with heat into at least two chemical substances.}atom economy {Ans: atom economy = molecular mass of the desired product ×100 sum of molecular masses of all products}unsaturated hydrocarbon {Ans: A hydrocarbon containing carbon-to-carbon multiple bonds.}van der Waals' forces {Ans: Very weak attractive forces between induced dipoles in neighbouring molecules.}electron shielding {Ans: The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons.}nucleophile {Ans: An atom (or group of atoms) that is attracted to an electron- deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.}activation energy {Ans: The minimum amount of kinetic energy that particles need to have in order to react when they collide}enthalpy, H {Ans: The heat content that is stored in a chemical system.}mechanism {Ans: A sequence of steps showing the path taken by electrons in a reaction.}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.}