GCSE AQA Chemistry Exam With All Answers

GCSE AQA Chemistry Exam With All Answers what is a compound - ANSWER contains atoms of two or more elements which are chemically combined in fixed proportions how can compounds be separated into their component elements - ANSWER chemical reactions or electrolysis why is the total mass of products equal to the total mass of reactants - ANSWER no atoms are lost or made what is a mixture - ANSWER contains two or more elements or compounds which are not chemically combined how can mixtures be separated - ANSWER physical processes - don't involve chemical reactions so no new substances are made what does filtration involve - ANSWER separates soluble solids from insoluble solids what does crystallisation involve - ANSWER obtains a soluble solid from a solution - mixture is warmed, water evaporates leaving crystals what does simple distillation do - ANSWER obtains a solvent from a solution what is fractional distillation used for - ANSWER separates mixtures in which the components have different boiling points what is chromatography used for - ANSWER separates the different soluble, coloured components of a mixture what is an atoms radius - ANSWER 0.1 nm / 1 x 10-10m what is the relative mass of an electron - ANSWER very small what is the relative mass of a proton / neutron - ANSWER 1 what is the relative charge of protons / neutrons and electrons - ANSWER +1, 0, -1 where is almost all the mass of an atom located - ANSWER in the nucleus how small is the radius of the nucleus in comparison with the radius of the atom - ANSWER less than 1/10,000 of the radius of the atom (mot of the atom is empty space) what is an atoms overall charge and why - ANSWER no overall charge (contain equal number of protons and electrons) atomic number and mass number location - ANSWER what is the atomic number - ANSWER number of protons what is the mass number - ANSWER number of protons and neutrons in the modern periodic table, how are the elements arranged - ANSWER in order of increasing atomic number