C2 Chemistry NANO-TECHNOLOGY OIL RIG Ionic Bonding Electrolysis: e.g. Water, Cl2, H2, HCl CH4, O2 Diamond Delocalised electrons Giant Covalent Structure High melting and boiling points, hard Strong covalent bonds Simple molecules Low melting and boiling points Weak intermolecular forces Does not conduct electricity Graphite only: Conducts electricity, soft and slippery between layers. -it has delocalised electrons- C2 Chemistry Covalent Bonding Non-metals sharing elections No charge An atom: Number of Protons = Number of Electrons Mass number = Protons + Neutrons Periodic table arranges elements by ATOMIC NUMBER (proton number/the small one) OIL RIG Oxidation is lose (of electrons) Reduction is gain (of electrons) Pure copper Impure copper (copper ore) Max 2 electrons Max 8 electrons E.g. 2,8,8 (Argon) The number of outer shell electrons match the group the element is found in. E.g. Lithium 2,1 is a group 1 element. Cu 2+ Describe this! Copper purification Impurities: include gold and silver (can be sold) Protons and neutrons both have a mass of 1 Electrolysis: Splitting up a substance using electricity Metallic Bonding Extracting Aluminium using electrolysis Sea of delocalised electrons Can carry a charge so metals conduct electricity Half equations Electrolysis needs: 2 electrodes An electrolyte (Ionic or molten substance) A power supply Ions move toward oppositely charged electrodes Remember: Atoms like to end up with full outer shells. + carbon electrodes need replacing as the corrode into CO2 Ionic Bonding When there are 2 possible products The less reactive forms at the electrode Alloy’s are stronger then pure metals a Add cryolite to lower melting point. Lose or gain an electron Get a charge +/- Attract one another! Electroplating Used for: Disinfectants, bleach and plastics Metal ions only arranged in layers ELECTROSTATIC ATTRACTION between +IONS and DELOCALISED ELECTRONS Group 1 Group 7 Brine: Salt water Is the negative electrode Used for: Margarine and HCl Use to improve: Appearance, stop corrosion and save money! Electrolysis of Brine Group 1 and 7 elements make good ionic partners, so do group 2 and 6! Metal ions slide over one another making them MALLEABLE Metals conduct HEAT well Used for: Bleach, paper and soap Giant Lattice Structure Always metals with non-metals + ION and – ION attracted by STRONG ELECTROSTATIC FORCES As a solid: High melting and Boiling Point Conducts electricity when melted or dissolved: Ions move freely and carry a charge NANO-TECHNOLOGY Means REALLY REALLY REALLY small !!!!!

When a reaction forms a SOILD(s) its called a PRECIPITATE Other techniques: Gas chromatography for separation, Mass Spectroscopy for identifying and finding molecular mass. Experimental Analysis Identifying what’s in a mixture. Paper chromatography I’d love to tell you a good chemistry joke but all the good ones Argon  Molecular ion peak = peak with the largest mass ISOTOPES are atoms of the same element with different numbers of neutrons Relative formula Mass Add the mass of each atom in the formula together e.g. CaCO3 40 + 12 + 16 + 16 + 16 = 100 Why use a machine? Advantages Disadvantages Quick Expensive Accurate Needs special training Analyse small amounts Interpreted by comparison only We compare the mass of any atom to Carbon 12 Additives improve appearance, taste and make food last longer! Moles 1 mole of any substance contains the same number of particles. (6.02x1023) Relative atomic mass or formula mass in grams is equal to one mole. e.g. 12g of carbon is one mole of carbon Plastics Using different monomers and conditions will change the type of polymer you produce. Hand warmers and self heating cans use exothermic reactions. Mixing two chemicals to produce heat (single use) or the formation of crystals in a supersaturated solution (reusable). Mass of element Total mass of compound x 100 = Percentage Mass e.g. % mass of carbon (12) in ethane C2H6 (30) 24 / 30 x 100 = 80% Thermosetting – don't melt ! – melt easily when heated Thermosoftening Cool packs use exothermic reactions – Good for sport injuries! All the carbon (12 + 12 = 24) When a reaction forms a SOILD(s) its called a PRECIPITATE Too removed a solid (s) from a reaction you FILTER it out ! Exothermic reactions give out heat to the surroundings(get hotter) e.g. Respiration & Combustion If you reaction gives you a dissolved product (aq) instead, you EVAPOURATE it out ! Catalysts Increasing the rate of a reaction can save money! Different reactions need different catalysts! Catalysts are often metals (if they escape they might harm the environment) Endothermic reactions take in heat from the surroundings (get colder) - speed up reactions without being used up e.g. Photosynthesis We can measure the rate of a reaction by looking at how fast solid reactants are used up, how quickly gas is produced or how quickly light is blocked (the disappearing cross) e.g. Sulfuric Acid + Magnesium -> Magnesium sulfate+ Hydrogen Collision Theory Reversible Reaction One way will be endothermic and the other will be exothermic In a closed system forward and backward reaction occur at equal rates e.g. Nitric Acid + Copper Oxide -> Copper nitrate + Water The rate of a reaction is speed up by increasing the: Temperature Surface area Concentration Or by adding a CATALYSIS Acid Salt Hydrochloric Acid Chloride Sulfuric Acid Sulfate Nitric Acid Nitrate For this: Anything that's not a metal on its own is a base When we increase the concentration/surface area we increase the frequency of particles colliding and reacting. Speeding up the reaction. When we increase the temperature the particles move faster, they are more likely to collide and do so with sufficient energy to react. Speeding up the reaction. Acid + Metal Salt + Hydrogen Acid + Base Salt + Water Steep line = fast reaction Flat line = A reactions that’s stopped! IMPORTANT Acids & Bases (Alkalis) Increase in pressure is the same as increase in concentration Acids – H+ Alkalis – OH- An increase of 10oC doubles the rate of a reaction For a reaction to take place we have to have the minimum amount of energy needed The ACTIVATION ENERGY Bases NEUTRALISE acids Alkalis are soluble bases pH Scale Find the pH using Universal Indicator

Balanced Equations Molecular Formula & Empirical Formula Molecular Formula : The actual number of atoms of each element in an individual molecule Empirical Formula : The simplest whole number ratio of the elements in the molecule Calculating the Empirical Formula 1) Use the same table and method given for calculating reacting masses but remove the ratio row. The question will either provide the grams of each element or the percentage. Assume percentages are the same figure in grams. e.g. 12% = 12g Percentage Yield This is used to compare our actual yield with our theoretical yield. Amount of product actually produced Maximum possible yield (Theoretical yield) x 100 e.g. 200 275 x 100 = 72.73 % Its rare to get 100% yield This is because some products can be left in apparatus or separating products from reactants is difficult. Sometimes it’s not everything reacts to begin with. Remember: Lots of waste reduces resources and cause extra pollution. A balanced equation has the same number of atoms for each element on both sides We can use this to find the ratio of moles that are needed to react with one another e.g. 1 CH4 molecule reacts with 2 O2 molecules 1:2 ratio Working out chemical formula… Use your data sheet! Question: A substance contains 24% carbon and 64% hydrogen. Calculate the its empirical formula. When doing an experiment if we know the grams used and the Molecular/Formula Mass we can calculate the moles e.g. In 24 g of carbon which has an Mr of 12 there would be 2 moles of carbon. 24/12 = 2 This is useful if we want to calculate how much product we would get from a specific amount of reactant THEORETICAL YIELD When you need to work out the ionic formula of a substance you will always need something from the positive ion column and something from the negative ion column. g Grams Chemical Carbon Hydrogen Grams 24 64 Mr 12 16 Moles 2 4 The charges should always cancel out! n Moles Mr Molecular/ Formula Mass e.g. What is the formula for silver oxide? 1) First identify the two ions you need. (one from each column) Ag+ and O2- 2) Balance the charges. Oxygen has 2 minus charges but silver only has a single positive charge. This means you’ll need two silvers to cancel out the one oxygen. ( + + ) Ag+ Ag+ = O2- ( - - ) Calculating Theoretical yield Question: How much CO2 would be produced by burning 100g of Methane (CH4) ? What if you need something that already has a small number? Put the whole ion in brackets! Cu (NO3)2 2) To get the simplest ratio divide all moles by the smallest calculated value 2/2 = 4/2 = 1 : 2 This gives you the number of each element present and the empirical formula C H2 3) Write the formula. When you know how many of each ion you need use this in the formula and ignore the charges. Ag2O Chemical CH4 CO2 Ratio 1 Grams 100 ? Mr 16 44 Moles 6.25 Try to work out: Magnesium oxide and Calcium chloride… 1) Put in the things you already know. You were given the grams of methane in the question. And can calculate the Mr using the periodic table. 2) Use the triangle to calculate the moles or methane used. 4) Now you have the Mr and the moles of CO2 you can use the triangle to calculate the grams that will be produced. 44 x 6..25 = 275 Answer: 100g of methane would make 275 g of CO2 Answers: MgO CaCl2 All figures in example calculations refer to the burning of methane in oxygen as shown in the balanced equation If you were told the compound had a mass of 28 you could calculate the molecular formula The Mr of CH2 is 14 28 /14 = 2 Therefore the molecular formula must be double the empirical one C2H4 3) Use the ratio from balanced equation to provide the moles of CO2 1 : 1 6.25 : 6.25

a) When sodium reacts with chlorine the sodium atoms change into sodium ions. Draw a diagram to show how sodium forms sodium ions. [2marks] b) Explain how the atoms are held together in sodium metal[3marks] 4. Copper is a good material for making a kettle because it has a high melting point. Explain why copper, like many other metals, has a high melting point. You should describe the structure and bonding of a metal in your answer. (6 marks) 6. Ethanol can be used as a fuel. The symbol equation for the combustion of ethanol is:   Balance this symbol equation. A car petrol tank can hold 50 kg of ethanol fuel. How much oxygen, in kg, is needed to react completely with this amount of fuel? 2a. Draw the covalent structure of methane [2marks] 2b. Explain why methane is a gas at room temperature [3 marks] 7. A student reacted small pieces of zinc with dilute acid to make hydrogen gas. Explain, in terms of particles, why increasing the concentration of the acid increases the rate of reaction. (2 marks) The student found that the reaction went twice as fast. Explain, as fully as you can, why an increase in temperature increases the rate of the reaction. (2marks) 5. Some toothpastes contain tin(ii) fluoride. This compound has the formula SnF2. A Calculate the relative formula mass (Mr) of SnF2. (Relative atomic masses: F = 19; Sn = 119) (2) B Calculate the percentage by mass of fluorine in SnF2. (2) C A tube of toothpaste contains 1.2 g of SnF2. Calculate the mass of fluorine in this tube of toothpaste. (1) 8. Copper(II) oxide is an insoluble base. Describe how you could make crystals of copper(II) sulfate from copper(II) oxide. (6marks) 3a. What does the term ‘nano’ tell you about the carbon nanotubes? (1)   3b. Like graphite, each carbon atom is joined to three other carbon atoms. Explain why the carbon nanotube can conduct electricity. (2)

Question Template Mark Scheme [1] Question 1a Question Template Mark Scheme [1] Question 3: A The tubes are very small (not ‘small’ on its own), or a few atoms across, or they are 1–100 nm across. b Three electrons in carbon’s outer shell are used in bonding, which leaves one electron free to move around or delocalise and carry current or charge. Q5 Give two marks for 157. If answer is incorrect either 2 × 19 + 119 or 119 + 19 = 138 gains one mark. b Give two marks for 24.2 (accept answers in the range 24 to 24.2038). If the answer is incorrect, 25 or 38/157 × 100 or 19/157 × 100 = 12 to 12.1 or 19/138 × 100 gains one mark (allow error carried forward from part a so 38/a × 100 gains two marks if calculated correctly). c 0.29 (accept answers in the range 0.28 to 0.3 and allow error carried forward from part b) Question1b: Electrons in the highest (occupied) energy level/outer shell are delocalised/ free (to move), leaving or surrounding positive ions (in regular lattice/arrangement), electrons attract/hold together the positive ions. 6 a b Mr ethanol = 46 50/46 = 1.09 1.09 × 3 moles oxygen = 3.27 3.27 × 32 = 104.6 kg of oxygen Question 4: Examples of the chemistry points made in the response: • giant structure/lattice atoms arranged in a regular pattern or in layers • sea of electrons or delocalised electrons or free electrons • awareness that outer shell/highest energy level electrons are involved • positive ions • (electrostatic) attractions/bonds between electrons and positive ions • bonds/attractions (between atoms or ions and electrons) are strong • a lot of energy/heat is needed to break these bonds/attractions. 2a 7a More particles in given volume or particles closer together/more crowded; particles collide more frequently or more often. B Three from: speed of particles increases; more frequent collisions; more energetic collisions; more particles have activation/minimum energy (needed) to react. 8 .Examples of the chemistry points made in the response: • Use dilute sulfuric acid. • Place acid in a beaker. • Warm the acid. • Add copper(ii) oxide. • In small amounts. • Until in excess or there is no further reaction. • Filter (to remove excess copper(ii) oxide). • Heat filtrate/solution to evaporate some water. • Allow solution to cool and crystallise or allow to evaporate slowly at room temperature. • Remove/filter crystals from remaining solution. 2b Weak intermolecular forces(weak attraction between molecules) Little energy required to break Low boiling point