Chemistry Definitions Flashcards
Definition of: acid
A substance that produces hydrogen ions (H+) when dissolved in water.
Definition of: acid-alkali indicator
A substance used to show if a solution is acidic or alkaline. It will have a different colour in each type of solution.
Definition of: acidic solution
A solution that has a pH < 7.
Definition of: acidic rain
Rain that has a pH < 5; produced when gases such as sulfur dioxide dissolve in rainwater.
Definition of: activation energy
The minimum energy required by colliding particles for reaction to occur.
Definition of: alkali
A base that dissolves in water to form hydroxide ions (OH-).
Definition of: alkaline solution
A solution that has a pH > 7.
Definition of: alkane
A saturated hydrocarbon with the general formula CnH2n+2.
Definition of: alkene
An unsaturated hydrocarbon with the general formula CnH2n.
Definition of: anion
A negatively charred ion. For example, Cl- , O^2- , OH- , NO3- , etc.
Definition of: atom
The smallest particle of an element that can take part in a chemical reaction.
Definition of: atomic number
The number if protons in the nucleus of an atom.
Definition of: base
A substance that neutralises an acid to form a salt.
Definition of: bauxite
The main ore of aluminium, from which aluminium is extracted.
Definition of: brine
A concentrated solution of sodium chloride in water.
Definition of: catalyst
A substance that speeds up a chemical reaction but which is chemically unchanged at the end of the reaction.
Definition of: cation
A positively charged ion. For example, Na+ , Mg^2+ , Al^3+ , NH4+ , etc.
Definition of: combustion
A chemical reaction involving burning.
Definition of: compound
A substance made up of two or more elements chemically combined together.
Definition of: contact process
The name of the industrial process used for making sulfuric acid.
Definition of: corrosion
A chemical reaction between a metal and oxygen.
Definition of: covalent bond
The force of attraction between the nuclei of two atoms and a pair of electrons shared between them.
Definition of: cracking
The process of breaking long-chain alkane molecules into short-chain alkanes and alkenes.
Definition of: crude oil
A naturally occurring mixture of many hydrocarbons.
Definition of: cryolite
A mineral of aluminium used in its molten form for dissolving aluminium oxide in the electrolytic manufacture of aluminium.
Definition of: decomposition
Breaking down a compound into simpler substances (either elements and/or other compounds).
Definition of: diffusion
The movement of particles (atoms, molecules or ions) from an area of high concentration to one of lower concentration.
Definition of: displacement reaction
A reaction in which one substance replaces another, for example chlorine displacing bromine from a bromide or zinc displacing copper from a copper salt or zinc displacing copper from copper(II) oxide.
Definition of: distillation
The process of separating a liquid from a solution of a solid in the liquid.