Category Archives: Chemistry

Chemistry Page Radioactivity is defined as the spontaneous breaking up of certain unstable nuclei, accompanies by the emission of radiation Radioactivity is detected by a Geiger-Muller tube. α particles (alpha) Alpha particles are helium nuclei with a positive charge and … Continue reading →

Chemistry Page It is important to have some knowledge about the major scientists involved in the major discoveries of chemistry. This is often only a short question in Q4 or a 3 marker in a long question, but its an … Continue reading →

Chemistry Page Intramolecular Bonds the bond within the molecule that holds the atoms together Intermolecular Forces forces between molecules Types of Intermolecular Forces 1. Van der Waals Forces Weak attractive forces caused by the movement of electrons within a molecule … Continue reading →

Chemistry Page Linear Shape BeH2 180° 2 bonding pairs Trigonal Planar BF3 120° 3 bonding pairs Tetrahedral CH4 109.5° 4 bonding pairs V-Shaped H2O 104.5º 2 bonding pairs and 2 lone pairs Pyramidal NH3 107º 3 bonding pairs and 1 … Continue reading →

Chemistry Page Catalysts work by providing an alternative reaction route with a lower activation energy. Intermediate Formation Theory of Catalysis The reactant molecules and the catalyst form and unstable intermediate complex that breaks up to form products and regenerate the … Continue reading →

Chemistry Page A catalyst is a substance that alters the rate of a chemical reaction but is not consumed in the reaction Heterogeneous catalysis involves reactants in different physical states i.e. liquid reacting with solid e.g.  MnO2 on H2O2 Homogeneous … Continue reading →

Chemistry Page Rate of Reaction is the change in concentration in unit time of any one reactant or product Average Rate – Change in Concentration                      Time taken Instantaneous Rate of Reaction is the rate at a particular point … Continue reading →

Chemistry page Oxidation Number the charge an atom appears to have when electrons are distributed according to certain rules Rules for assigning charges Free elements: 0 e.g. O2 – o Sum of oxidation numbers: 0 e.g. H2O – o Oxidation … Continue reading →

Chemistry page This is the theory section of acid-base titrations. Experiments make up the majority of this section. 1 molar = 1 mole per litre e.g. 1 mole Na2CO3 = 106g/L : 0.1 molar = 1.6g/L Concentration is the amount … Continue reading →