AQA GCSE Chemistry - Paper 1 Questions & Answers

What is the charge of a proton? - ANSWERS+1 What is the charge of a neutron? - ANSWERS0 What is the charge of an electron? - ANSWERS-1 What is the relative mass of a proton? - ANSWERS1 What is the relative mass of a neutron? - ANSWERS1 What is the relative mass of an electron? - ANSWERSVery small How many types of atoms do elements contain? - ANSWERSOnly one type What are compounds? - ANSWERSSubstances containing two or more different elements that are chemically bonded together What are mixtures? - ANSWERSSubstances containing two or more different elements that are not chemically bonded together What pattern is formed from carrying out paper chromatography? - ANSWERSChromatogram Which method of separation is useful to separate an insoluble solid from a liquid? - ANSWERSFiltration Which method of separation is useful to separate a soluble solid from a liquid? - ANSWERSEvaporation or Crystillisation Which method of distillation separates liquids with similar boiling points? - ANSWERSFractional distillation Who discovered that the plum pudding model was wrong? - ANSWERSErnest Rutherford Who devised an experiment that proved the existence of the neutron? - ANSWERSNiels Bohr Why did Mendeleev leave gaps in his Table of Elements? - ANSWERSTo ensure that elements with similar properties stayed in the same groups. The gaps indicated the existence of undiscovered elements and allowed Mendeleev to predict what their properties might be How are the group number and the number of electrons in the outer shell of an element related? - ANSWERSThe group number tells you how many electrons are in the outer shell of an element. E.g. sodium is in Group 1 therefore it has 1 electron on its outer shell What kind of ions do metals form? - ANSWERSPositive Where are the non-metals on the periodic table? - ANSWERSOn the right hand side Give three properties which are specific to transition metals - ANSWERS1) They can form more than one ion e.g cobalt form Co2+ 2) They are often coloured, therefore compounds which contain them are colourful e.g. potassium chromate is yellow 3) They often make good catalysts e.g. nickel based catalysts are used in the hydrogenation of alkenes State three trends as you go down Group 1 - ANSWERS1) Increased reactivity - the outer electron is more easily lost as the attraction between the nucleus and the electron decreases because the electron is further away from the nucleus 2) Lower melting and boiling points 3) Higher relative atomic mass What are the products of the reaction of a Group 1 metal and water - ANSWERSHydrogen gas and a metal hydroxide E.g. sodium + water --> sodium hydroxide + hydrogen What's the difference between the hardness of Group 1 and transition metals? - ANSWERSTransition metals are harder, denser and stronger than Group 1 metals What's the difference between the reactivity of Group 1 and transition metals? - ANSWERSGroup 1 metals are much more reactive than transition metals What's the difference between the melting points of Group 1 and transition metals? - ANSWERSTransition metals have higher melting points than Group 1 metals What trends occur as you go down Group 7? - ANSWERS1) They become less reactive - it's harder to gain an extra electron because the outer shell's further from the nucleus 2) They have higher melting and boiling points 3) They have higher relative atomic masses What is the charge of the ions that halogens form when they react with metals? - ANSWERSThey form negative ions What is the trend in boiling point as you go down Group 0? - ANSWERSThe boiling points increase What subatomic particles does the nucleus contain? - ANSWERSProtons and neutrons What is relative atomic mass? - ANSWERSThe mass number which refers to the element as a whole How are positive ions formed? - ANSWERSA metal atom loses electrons How are negative ions formed? - ANSWERSA non-metal gains electrons What is air a mixture of? - ANSWERSGases, mainly nitrogen, oxygen, carbon dioxide and argon What is crude oil a mixture of? - ANSWERSDifferent length hydrocarbon molecules How can you separate substances in a mixture? - ANSWERSChromatography What is simple distillation used for? - ANSWERSSeparating out a liquid from a solution E.g. separating pure water from seawater How were elements arranged in the early 1800s? - ANSWERSBy their physical and chemical properties and their relative atomic mass How are columns arranged? - ANSWERSElements with similar properties What are the three similar basic properties of metals? - ANSWERS1) They're strong but are malleable 2) They're great at conducting heat and electricity 3) They have high boiling and melting points What is the product of the reaction of a Group 1 metal with chlorine? - ANSWERSA metal chloride salt E.g. sodium + chlorine --> sodium chloride What is the product of the reaction of a Group 1 metal with oxygen? - ANSWERSA metal oxide, depending on the Group 1 metal -Lithium + oxygen --> lithium oxide -Sodium + oxygen --> sodium oxide + sodium peroxide -Potassium + oxygen --> potassium peroxide + potassium superoxide What are halogens? - ANSWERSNon-metals in Group 7 with coloured vapours What colour is fluorine? - ANSWERSA very reactive, poisonous yellow gas What colour is chlorine? - ANSWERSA fairly reactive, poisonous dense green gas What colour is bromine? - ANSWERSA dense, poisonous red-brown volatile liquid What colour is iodine? - ANSWERSA dark grey crystalline solid or a purple vapour What do halogens exist as? - ANSWERSMolecules - pairs of atoms What do halogens form? - ANSWERS1) Molecular compounds - halogens share electrons via covalent bonding with other non-metals too achieves a full outer shell 2) Ionic compounds with metals - they form 1- ions called halides What do noble gases exist as? - ANSWERSMonatomic gases - single atoms not bonded to each other What are the noble gases at room temperature? - ANSWERSColourless gases Are the noble gases flammable? - ANSWERSNo - they're non-flammable Why does the boiling point of noble gases increase as you move down the group? - ANSWERSThere's an increase in the number of electrons in each atom leading to greater intermolecular forces between them which to be overcome Paper Chromatography - Method - ANSWERS1) Draw a pencil line near the bottom of a sheet of filter paper 2) Add a spot of ink to the line & place the sheet in a beaker of solvent e.g. water - the solvent used depends on what's being tested - some compounds dissolve well in water, but sometimes other solvents e.g. ethanol are needed 3) Ensure the ink isn't touching the solvent - you don't want it to dissolve 4) Place a lid on top of the container to stop the solvent evaporating 5) The solvent seeps up the paper, carrying the ink with it 6) Each different dye in the ink will move up the paper at a different rate so that the dyes will separate out - each dye will form a spot in a different place, 1 spot per dye in the ink 7) If any of the dyes in the ink are insoluble in the solvent used, they'll stay on the baseline 8) When the solvent has nearly reached the top of the paper, take the paper out of the beaker & leave it to dry Simple Distillation - Method - ANSWERS1) The solution is heated. The part of the solution that has the lowest boiling point evaporates first 2) The vapour is then cooled, condensed & is collected 3) The rest of the solution is left behind in the flask What is the problem with simple distillation? - ANSWERSYou can only use it to separate things with very different boiling points - if the temperature goes higher than the boiling point of the substance with the highest boiling point, they will mix again Fractional Distillation - Method - ANSWERS1) Put your mixture in a flask & stick a fractionating column on top. Then you heat it 2) The different liquids will all have different boiling points - they'll evaporate at different temperatures 3) The liquid with the lowest boiling point evaporates first. When the temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column 4) Liquids with higher boiling points might also start to evaporate, but the column is cooler towards the top, therefore they will only get part of the way up before condensing & running back down towards the flask 5) When the first liquid has been collected, you raise the temperature until the next one reaches the top Radius of an atom - ANSWERS0.1 nanometers Radius of a nucleus - ANSWERS1/10,000 of the radius of an atom What type of ion do elements from Group 1 form? - ANSWERSPositive ions What type of ion do elements from Group 7 form? - ANSWERSNegative ions Describe how an ionic bond forms - ANSWERSWhen a metal and a non-metal react together, the metal loses its one electron on its outer shell to form a positively charged ion. This one electron is gained by the non-metal to complete its outer shell, forming a negative ion. Describe the structure of a crystal of sodium chloride - ANSWERSIt's a giant ionic lattice. The positive sodium and negative chlorine ions form a closely packed regular arrangement and there are very strong electrostatic forces of attraction between the oppositely charged ions. List the main properties of ionic compounds - ANSWERS1) High melting and boiling points - many strong bonds between the ions 2) They can't conduct electricity when they're solid - the ions are held in a fixed arrangement therefore they can't pass on the electrical current. 3) They can conduct electricity when they're liquids because the ions are free to move therefore they can pass on the electrical current. 4) They dissolve easily in water - they are free to move in the solution and can carry electrical current. Describe how covalent bonds form - ANSWERSWhen two non-metals bond together, they share electrons to make covalent bonds. The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces - this makes covalent bonds very strong. Explain why simple molecular compounds typically have low melting and boiling points - ANSWERSThe intermolecular forces between the atoms are very weak, therefore it takes only a small amount of energy to break them apart. Describe the structure of a polymer - ANSWERSPolymers are long chains of repeating units joined together to make a long molecule. Between the atoms are strong covalent bonds. Give three examples of giant covalent substances - ANSWERS-Diamond -Graphite -Silicon Dioxide Explain why graphite can conduct electricity - ANSWERSIt contains delocalised electrons which can carry electrical charge What is metallic bonding? - ANSWERSThe electrons in the outer shell of a metal atom are delocalised. There are strong forces of electrostatic attraction between the positive metal ions and the negative electrons. These forces of attraction hold the atoms together in a regular structure. List three properties of metals and explain how metallic structure causes each property - ANSWERS1)Solid at room temperature - they have very high melting and boiling points because a lot of energy is needed to break the strong electrostatic forces of attraction between the metal atoms and delocalised electrons. 2)Good conductors of heat and electricity - the delocalised electrons can carry electrical current and thermal energy through the structure. 3)Malleable - the layers of metal atoms can slide over each other Explain why alloys are harder than pure metals - ANSWERSWhen two metals are mixed together, both of their atoms are different sizes which causes a disruption in the neat layers of metal atoms. This makes it more difficult for the layers to slide over each other. Name three states of matter - ANSWERSSolid, liquid and gas State Symbols - ANSWERSsolid - s liquid - l gas - g aqueous - aq What is the name of the temperature at which a liquid becomes a gas? - ANSWERSBoiling