chem notes

• Acid


  Proton donor, substance that acts as a source of hydrogen ion (H+), has pH<7
• Activation energy


  Minimum amount of energy required for collision to be successful, to result in a reaction
• Alkali metals


  Group 1 elements including lithium, sodium, potassium, rubidium, caesium and francium
• Allotropes


  Different forms of the same element, e.g. carbon has three allotropes: diamond, C60 and graphite
• Alloy


  Mixture of metals, e.g. steel which is alloy of iron and carbon
• Anaerobic


  In absence of air
• Anhydrous


  Absence of water
• Anion


  Negative ion formed by gaining electrons
• Anode


  Positive electrode, attracts negative anions, oxidation reaction occur
• Anomalous result


  Result that doesn't fit in with the pattern of the others
• Aqueous


  Dissolves in water
• Atomic number


  The number of protons in the nucleus of an atom
• Base


  Proton acceptor, substance that neutralise an acid, soluble base is called an alkali, acts as a source of hydroxide ions (OH-)
• Calorimetry


  Measuring heat given out or taken in by a chemical reaction
• Catalyst


  Substance that speeds up a chemical reaction by providing an alternative pathway of lower activation energy, not used up and remain chemically unchanged at the end of the reaction
• Catalytic convertor


  A device used in cars to convert oxides of nitrogen and carbon monoxide into harmless nitrogen and carbon dioxide gases, uses platinum and rhodium as catalysts
• Cathode


  Negative electrode, attracts positive cations, undergoes reduction reaction
• Collision theory


  States that for a reaction to occur, the reactants particles must collide with each other's and the collision needs to have sufficient energy and the correct orientation
• Covalent bonding


  A strong force between the nuclei of the atoms making up the bond and the shared electrons, sharing of electrons between non-metal atoms
• Damp


  Slightly wet
• Dehydration


  Removal of water
• Delocalised electrons


  Electrons that are free to move throughout the whole structure
• Dependent variable


  What you measure in the experiment
• Diatomic


  A molecule that contains two atoms
• Diffusion


  Random movement of particles from an area of high concentration to an area of low concentration to distribute evenly
• Double bond


  Atoms sharing two pairs of electrons (4 electrons in total) in a covalent bond
• Dry ice


  Solid carbon dioxide
• Ductile


  Property of metals that allows it to be drawn into wires
• Dynamic equilibrium


  Equilibrium means the concentration of reactants and products in a reversible reaction remain constant, dynamic means the reaction are still continuing but the rate of the forward reaction is equal to the rate of the backward reaction
• Electrolysis


  The chemical change caused by passing electric current through a compound that is either molten or solution

  
• Electrolyte


  A liquid that undergoes electrolysis, they are molten ionic compounds or solutions containing ions
• Electrostatic attraction


  Force of attraction between oppositely charged particles
• End point


  A point at which the indicator changes colour in titration
• Endothermic


  Reactions in which heat energy is taken in from the surrounding
• Enthalpy change


  The amount of heat energy taken in or given out in a chemical reaction
• Excess


  Having more than enough of a reactant to react with all of something else
• Galvanisation


  A method of preventing iron from rust by covering it with a layer of zinc
• Halogen


  Group 7 elements including fluorine, chlorine, iodine, bromine
• Group


  A vertical column in the periodic table, elements in the same group have same number of outer shell electrons

  
• Hydrated


  Containing water