Q4 Fill in the blanks

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1 Q1 Draw the electronic structure of the ions in Sodium chloride Q2 Draw the electronic structure of the ions in Magnesium oxide Q3 Draw the electronic structure of the ions in Calcium chloride Q4 Fill in the blanks Charge Relative mass proton electron neutron Q5 What type of bonding is present in Water (H 2 O), Hydrogen (H 2 ), Ammonia (NH 3 ), Hydrogen Chloride (HCl), Methane (CH 4 ) and Oxygen (O 2 )? Q6 Draw out the electron structure to show the covalent bonding in Hydrogen H 2 Q7 Draw out the electron structure to show the covalent bonding in Methane CH 4 Q8 Draw out the electron structure to show the covalent bonding in Water H 2 O Q9 Draw out the electron structure to show the covalent bonding in Oxygen O 2

2 A3 A2 A1 A6 A5 Covalent bonding (sharing electrons). This is because they are all molecules of non-metals A4 Charge Relative mass proton +1 1 electron -1 Almost 0 neutron 0 1 A9 A8 A7

3 Q10 What is chemical bonding? Q11 What type of bonding involves transferring electrons (gaining or losing electrons) Q12 What type of bonding involves sharing of electrons? Q13 What is the structure of an Ionic compound Q14 Some covalent substances (H 2, CO 2, H 2 O, CH 4 ) make simple molecules. What are the properties of simple molecules? Q15 Give two examples of giant covalent structures (macromolecules) Q16 What is the structure of Metals? Q17 HT only How are metal atoms held together in a metallic structure? Q18 HT only Why do simple covalent molecules have low melting and boiling points?

4 A12 Covalent bonding. Compounds made from nonmetals make molecules by sharing electrons. A11 Ionic bonding. Metal atoms lose electrons to make positive ions. Non-metal atoms gain electrons to make negative ions. A10 Chemical bonding is transferring or sharing electrons to get a stable electron structure (like the noble gases) A15 Diamond and Silicon dioxide (also Graphite) A14 Simple molecules make solids, liquids or gases with low melting and low boiling points A13 Ionic compounds are giant structures (lattice) of ions held together by strong electrostatic forces between oppositely charged ions A18 The only forces to overcome on heating are the weak intermolecular forces between the covalent molecules. A17 The electrons in the outer energy levels of the metal atoms are delocalised and free to move. There is then a strong electrostatic attraction between the positive metal ions and the negative electrons. A16 Metals consist of a giant structures, with atoms arranged in a regular pattern.

5 Q19 How do you find A r and M r for a substance Q20 What is the empirical formula? HT Q21 How do you calculate the percentage of an element in a compound? Q22 What is a mole (in chemistry)? Q23 HT How do you work out percentage yield? Q24 Why is it important to achieve a high yield in industry? Q25 Q26 Q27 What are reversible reactions? What is nanoscience? What is a shape memory alloy?

6 A21 A r of element x 100 M r of compound The percentage of Na in NaOH is: 23 (A r of Na) x 100 = 57.5% 40 (M r of NaOH) A20 The formula showing the simplest ratio of elements present in a compound. A19 A r (relative atomic mass) can be read from the periodic table for any element. The M r (relative molecular mass) is the sum of A r in a formula: NaOH = = 40 A24 This minimises energy wasted, conserves Earth s resources, reduces pollution and makes a greater profit. A23 Mass of chemical obtained Maximum mass of chemical possible x 100 The maximum mass possible is calculated from the reaction equation. A22 A mole of any substance is its relative formula mass (M r ) in grams. Mass (g) Moles = A r or M r A27 If a shape memory alloy is deformed, it returns to its original shape on heating. A26 Nanoscience is the study of small particles that are between 1 and 100 nanometres in size A25 In reversible reactions the products can react again to make the original reactants. These are shown with a double arrow e.g. NH 4 Cl NH 3 + HCl

7 Q28 HT Why are metals such good conductors of heat? Q29 What affects the properties of polymers? Q30 What is the difference between thermo-setting and thermo-softening polymers? Q31 What are food additives? Q32 How can we detect artificial food colourings? Q33 What are the advantages of instrumental methods of analysis? Q34 What two instruments or techniques are needed to analyse compounds in a sample mixture? Q35 What is the equation to work out the rate of reaction? Q36 What are the 4 main things affecting the rate of a reaction?

8 A30 Thermo-softening polymers are softened or melt easily when heated. Thermo-setting polymers will not soften on heating and will char. HT Thermosetting polymers have strong cross links (covalent bonds). A29 The properties are affected by the monomers used and the reaction conditions A28 Delocalised electrons can flow through the metal lattice allowing electrical current and heat energy to be transferred quickly. A33 Modern instrumental techniques are: faster, more accurate and more sensitive. A32 Paper chromatography. A31 Food additives are added to food to improve flavour, appearance and shelf life. A36 Temperature Surface area Concentration (of solutions) or Pressure (of gases) Presence of a catalyst A35 Rate of reaction = or Rate of reaction = amount of reactant used time amount of product formed time A34 1) Gas chromatography which separates the compounds 2) Mass spectrometer that identifies compounds based on their relative molecular mass (M r )

9 Q37 What is collision theory? Q38 Explain how surface area affects the rate of a reaction. Q39 Explain how temperature affects the rate of a reaction. Q40 Explain how concentration affects the rate of a reaction. Q41 Explain how pressure affects the rate of a reaction (in gases) Q42 What do catalysts do to the rate of a reaction? Q43 What are the advantages and disadvantages of using catalysts in industry? Q44 What is an exothermic reaction? Q45 What is an endothermic reaction?

10 A39 The higher the temperature, the faster the rate of reaction. (pattern) This is because the frequency and energy of collisions is increased between reacting particles. More collisions are successful as they have exceeded activation energy. (reason) A38 The larger the surface area, the faster the rate of reaction (pattern) This is because the frequency of collisions is increased between reacting particles (reason) A37 Particles must collide before they can react. Not all collisions cause a reaction. The minimum energy the particles must have in order to react is called Activation energy. A42 Catalysts speed up the rate of reaction, but they are not used up in the reaction. Different catalysts are needed for different reactions. A41 The greater the pressure, the faster the rate of reaction. (pattern) This is because the frequency of collisions increases between reacting particles. (reason) A40 The greater the concentration, the faster the rate of reaction. (pattern) This is because the frequency of collisions increases between reacting particles. (reason) A45 A reaction which absorbs heat energy from its surroundings. A44 A reaction which releases heat energy to its surroundings. A43 Advantages: faster reactions and reduced energy costs. Modern catalysts (nanoparticles) have less waste and are more efficient Disadvantages: catalysts are often harmful transition metals or their compounds which can be toxic in the environment

11 Q46 How is energy transferred in a reversible reaction? Q47 What products use the energy from exothermic reactions? Q48 What products use the cooling effect of endothermic reactions? Q49 What is an acid? Q50 What are bases and alkalis? Q51 Making salts 1 What salts can we make from hydrochloric, sulphuric and nitric acids? Q52 Making salts 2 What happens when a metal and acid react? Q53 Making salts 3 How do we make a salt from an acid and insoluble base? Q54 Making salts 4 What happens when an acid and alkali react?

12 A48 Instant cold packs for sports injuries or burns. A47 Hand warmers and self-heating cans. A46 The amount of energy released when the reaction goes in one direction is exactly the same as the amount of energy absorbed when it goes in the other direction. A51 Acid Formula Type of salt Hydrochloric acid HCl chlorides Sulphuric acid H 2 SO 4 sulphates Nitric acid HNO 3 nitrates A50 A base is a substance that can neutralise an acid. Bases that are soluble in water and are called alkalis, they produce OH - ions. The ph of alkalis are more than 7 (ph from 7-14, a ph of 14 is more alkaline than a ph of 8) A49 A substance that produces H + ions when it is dissolved in water. The ph of acids is less than 7 (ph from 0-7, a ph of 2 is more acidic than a ph of 5) A54 acid + alkali a salt + water A53 1) add acid to insoluble base 2) heat gently and then filter off the excess (un-reacted) base 3) evaporate the water from the solution to make crystals of the salt acid + base salt + water H 2 SO 4 + CuO CuSO 4 + H 2 0 A52 Metal + Acid a Salt + Hydrogen (MASH)

13 Q55 Making salts 5 How do we make insoluble salts? Q56 What is electrolysis and what type of substances can we electrolyse? Q57 What happens to the ions in electrolysis? Q58 How does water affect electrolysis? Q59 How is aluminium extracted from aluminium oxide (ore)? Q60 What happens at the electrodes during aluminium oxide electrolysis? Q61 What is produced when we electrolyse brine (sodium chloride solution)? Q62 What are the products of brine electrolysis used for? Q63 How do we electroplate objects?

14 A57 Positive (usually metal) ions move to the negative electrodes. Negative ions move to the positive electrodes. Negative ions are oxidised, positive ions are reduced. Oxidation Is Loss of electrons, Reduction Is Gain of electrons (OILRIG) A56 Electrolysis is where a substance is broken down using electricity. Ionic compounds which are in solution or are molten can be used as their ions are free to move. A55 Insoluble salts are made when two solutions react to produce a precipitate. This can be used to remove unwanted ions from solution, e.g from industrial waste water. A60 Negative electrode: Al 3+ ions gain 3 electrons and become aluminium atoms, molten aluminium is tapped off. Positive electrode: O 2- ions lose 2 electrons and become oxygen atoms which pair off to give molecules of oxygen gas (O 2 ) A59 The aluminium oxide is mixed with molten cryolite, and extracted by electrolysis. Cryolite is essential to reduce the melting point. A58 Hydrogen and metal ions both go to the negative electrode, the less reactive element is made there. (look at the reactivity series on the data sheet in the exam) A63 The metal object to be plated is placed at the negative electrode in an electrolysis cell. The metal to coat the object with is placed at the positive electrode. A62 Chlorine: to make bleach and plastics Hydrogen: to make margarine Sodium hydroxide: to make bleach, paper and soap A61 Chlorine gas Hydrogen gas Sodium hydroxide solution