Sodium Thiosulphate Investigation

number. 15Which of these elements has the greatest atomic number?Element B. 16What is the electron arrangement of element C?2.8.7 17What is the electron arrangement of element E?2.8.1 18Which of the elements are very reactive metal and why?Elements D & E - they are in Group 1 (The alkali metals). 19Which of the elements is a very unreactive non-metal and why?Element F - it is in Group 0 (The noble gases). 20Name the first four halogens.1. Fluorine 2. Chlorine 3. Bromine 4. Iodine 21What happens to the reactivity of the halogens as you go down the group (increasing atomic number)?They become less reactive. 22What happens to the colour of these elements down the group?They become darker in colour. 23What happens to the boiling point of these elements down the group?Their boiling points increase. 24What does fluorine look like?A pale yellow gas. 25What does chlorine look like?A green gas. 26Name two uses for chlorine.1. Killing bacteria in water. 2. Making bleaches. 27What does bromine look like?A red -brown liquid (which evaporates easily to make an orange-brown gas). 28What colour is bromine dissolved in water?Orange-brown. 29What is the name of the compound formed when potassium reacts with bromine?Potassium bromide. 30What colour is this compound when dissolved in water?Colourless. 31What does iodine look like?A shiny grey-black solid (which produces a purple gas when gently heated). 32What colour is iodine dissolved in water?Brown. 33What is this iodine solution used for?An antiseptic. 34What is the name of the compound formed when sodium reacts with iodine?Sodium iodide. 35What colour is this compound when dissolved in water?Colourless. 36What is the name of compounds of the halogens?Halides. 37List two observations when sodium reacts with chlorine.1. The metal burns with a yellow flame. 2. A white solid is produced. 38What is the name of the product of this reaction?Sodium chloride. 39What is its chemical formula?NaCl 40List two observations when iron wool reacts with chlorine.1. The metal glows red. 2. A brown solid is produced. 41What is the name (and chemical formula) of the product this time?Iron chloride (FeCl3). 42What is formed in this reaction: bromine + potassium iodide?potassium bromide + iodine 43Which of these compounds will NOT react with chlorine: a) sodium fluoride; b) potassium bromide?sodium fluoride (Chlorine is less reactive than fluorine and so cannot displace it from fluorides.) 44What is a compound?A substance made by chemically joining two or more elements together. 45"Compounds have similar properties to the elements they are made from." Is this true or false?False - they have completely different properties, eg sodium chloride is nothing like either sodium or chlorine. 46What is the name for the substances on the left of a chemical equation?The reactants (or starting materials). 47What is the name for the substances on the right?The products. 48What do the symbols (s), (l) and (g) stand for in chemical equations?Solid, liquid and gas 49What does the symbol (aq) stand for in chemical equations?Aqueous (which means dissolved in water). 50What is meant by reaction rate?How fast a reaction goes. 51List four ways of increasing the rate of a reaction.1. Increasing the temperature. 2. Increasing the concentration of a reactant. 3. Increasing the surface area of a solid.4. Adding a catalyst. 52What is a catalyst?A chemical which speeds up a reaction but which does not get used up. 53Does the catalyst appear in the chemical equation for the reaction?No (because it does not get used up). 54What are enzymes?Catalysts produced by living things. 55Why don't enzymes work if the temperature is too high?They become denatured (damaged) by the heat. 56What two things about line A show that it represents a faster reaction?1. It starts more steeply. 2. It levels off sooner. 57How can you tell that both lines A and B were obtained using the same amounts of the reactants?They both produced the same amount of product in the end. 58Increasing the temperature makes the particles move around more quickly. Give two reasons why this makes the reaction faster.1. The collisions occur more often. 2. More of the collisions have enough energy to lead to a reaction