Chemical - Atoms, elements,mixtures and compounds 0.0 / 5 ? ChemistryAtomsGCSEAQA Created by: LunaShomeiRoseCreated on: 05-10-18 17:49 In a ____ all of the atoms are the same Element 1 of 28 What is a compound? Two/more different elements chemically combined together in a fixed proportion. 2 of 28 Do compounds have different/same properties from the elements they're made from. Different. 3 of 28 How can compounds be split back into their original elements? With a chemical reaction. 4 of 28 What's the difference between a compound and a mixture? Compounds are two/more elements chemically bonded, but a mixture is two/more elements/compounds that are not chemically bonded. 5 of 28 How do you separate a mixture? Use a physical technique instead of a chemical one. 6 of 28 List physical techniques that could be used. Filtration, distillation, Crystallization or chromatography 7 of 28 What's a molecule? Has any elements chemically combined, even if same element. 8 of 28 What does unsalable mean? Unable to dissolve in water 9 of 28 What is filtration used for? Separating a mixture (separate an insoluble solid from a liquid - solids in liquid) 10 of 28 What is crystalisation used for? Separating a soluble solid (dissolves) from a liquid. 11 of 28 What does (aq) mean? [e.g. NaCl(aq)] Means the molecule (NaCl) is dissolved in water - Aqueous solution. 12 of 28 So if you left the solution of NaCl(aq) to evaporate, what would happen to it's form? It would leave solid NaCl crystals. so the (aq) would now be (s) instead as it's no longer dissolved in water. 13 of 28 What is simple distillation used for? Separates liquids from a solid, storing the liquid. 14 of 28 What does fractional distillation separate? Two/more liquids with different boiling points. 15 of 28 What does chromatography separate? Substances based on their different solubilities (ability to dissolve). 16 of 28 Example of chromatography: which pens contain only one colour, and which contain a mixture. So, what's the first step to investigate this? Get piece of chromatography paper, and draw a pencil line near the bottom 17 of 28 We then add dots of the colours we want to test, on the line. We then place the paper into a ____ Solvent (liquid that will dissolve other substances. e.g. water) 18 of 28 It then dissolves the ink. But which way does the solvent move on the paper? Up 19 of 28 There are two different phases in chromatography. Which are... Paper = stationary phase (as it doesn't move). Solvent = mobile phase (as it does move) 20 of 28 If there's only one colour spot as a result, it means... The pen was made from a single pure substance 21 of 28 If the spot separates into different colours, it means... That colour was a mixture of x (how ever many colours it separated into) different substances 22 of 28 Why does this method work? As each chemical in the mixture will be attracted to the paper (stationary stage) to a different extent. 23 of 28 How far will chemicals that are strongly attracted to the stationary stage move up the paper? Not very far 24 of 28 What about weakly attracted chemicals? Will move further up the paper. 25 of 28 A ___ chemical will produce a single spot in all solvents. A pure chemical. 26 of 28 The chemicals in a ___ may separate into different spots, depending on the solvent. In a mixture 27 of 28 What did ancient Greeks believe atoms were like? Atoms are tiny spheres that can't be divided. 28 of 28
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