AQA C1 Atomic Structure What s in an atom? Elements in the periodic have different sizes of atoms. The size of the atoms depends on the number of protons, electrons and neutrons they have. Each element box has 2 numbers the smaller one is called the Atomic number and is the number of protons and electrons in an atom. This is always the smaller of the 2 numbers. Fluorine has 9 electrons and 9 protons because the atomic number is 9. Fluorine has 10 neutrons because that is the difference between the Mass Number and Atomic Number. In an atom, protons and electrons are always equal and so the charge of an atom is neutral. overall neutral as the number of positive charges is charged take up shells equal to the number of negative electrons. The neutrons and protons positions in the central nucleus. The electrons take up positions in this means that electrons orbit the nucleus. Each shell can only have a certain number of electrons. The first shell can have 2 electrons before being full. The 2 nd and 3 rd can take up to 8. Atoms that have only full shells of electrons are not reactive Ionic Bonding Covalent Bonding Metal atoms bond with non-metals using IONIC bonding. This is where a metal atom loses electrons to make a full outer shell. The metal becomes a positive ion. The non-metal atom gains these electrons to form a negative ion with a full shell. Every STRAIGHT line between atoms on the paper is covalent bond. See The other form of bonding is for nonmetals to form covalent bonds. This hydrocarbons where outer shells from 2 atoms OVERLAP and share electrons to fill the shell. Each covalent bond is pair of electrons being shared.
AQA C1 Limestone Science Obtaining and making Limestone Useful Limestone is a key raw material for the building industry. It is sedimentary rocked, formed millions ago form the remains of sea dwelling creatures underground. Sometimes, calcium carbonate is referred to a locked up CO2. The first step to change limestone or calcium carbonate is called THERMAL DECOMPOSITION. Heating breaks up the carbonate causing this reaction. Calcium Carbonate Calcium Oxide + CaCO 3 CaO + CO 2 Calcium oxide mixed with clay is the main basis for cement. When water is added to the Calcium oxide, it reacts to change it into Calcium Hydroxide. This is also know as Limewater. Should we use Quarries? ADVANTAGES They provide employment for hundreds of people The supply of Limestone is important for cement, concrete and glass Limestone Cycle ADVANTAGES They leave massive holes which are eyesore and damage and disfigure the environment The heavy traffic creates a range of pollution issues from local dust clouds to increased CO2 production Calcium Oxide + Water Calcium Hydroxide CaO + H 2 0 Ca(OH) 2 Limewater turns cloudy when carbon dioxide is bubbled through it. Copper carbonate is another carbonate that also decomposes on heating with a visible colour change. Calcium carbonate will also react with acids to form a salt, water and CO 2. Limestone based buildings are susceptible to acid rain corrosion. Calcium carbonate can be changed to Calcium Oxide and Calcium Hydroxide. Calcium Hydroxide is better known as limewater and when it turns cloudy with CO 2, the white cloud is fact Calcium Carbonate. Hence these reactions are called a cycle. Scan this video Learn Formula CaCO3 Calcium Carbonate Ca(OH)2 Calcium Hydroxide CaO Calcium Oxide CO2 Carbon Dioxide
AQA C1 Reactivity of Metals Making Iron using Blast furnace Smelting Copper Copper rich compounds don t always need to be heated with carbon. Heating with very hot oxygen in a reaction called is enough to remove the bonded sulphur and form impure copper which can then be purified using electrolysis. Very few metals are found in nature. Only the unreactive metals like gold or platinum are found this way. The main metals we use in society are found in metal rich rocks called ORES. Scientists then have to get the metal out of the rock in order to make the metal useful. One way to do this is the blast furnace. Here, carbon in the form of coke can be used to strip the oxygen from Iron Oxide. This is referred to as reduction. iron oxide + carbon iron + carbon dioxide 2Fe 2 O 3 + 3C 4Fe + 3CO 2 Why is CARBON used to make some metals? What is an ALLOY? Carbon and the BLAST FURNACE can be used only for metals that are lower than CARBON in the reactivity series. So metals like IRON and COPPER are made using this method. Aluminium can not be made using this method because it is more reactive than carbon Pure metals can be quite soft. Surprising I know. To make metals stronger, they can be mixed together. This helps them to reduce them to be less reactive. For example, iron rusts easily with water but when iron is alloyed with carbon and other metals, it becomes less reactive and does not rust easily Alloys are much stronger than pure metals and modern alloys can be made into shapes memory alloys. Glasses frames and mouth braces are examples of these being used.
AQA C1 Making Copper Purifying Copper ANODE REACTION Cu - Cu 2+ + 2e- CATHODE REACTION Cu 2+ + 2e- Cu Impure copper is not good enough to be used in electrical wires and copper pipes. It must purified and the process used for this is electrolysis. Impure copper from either smelting or the blast furnace is made into a POSTIVE electrode called an ANODE. Existing PURE copper is made into a NEGATIVE electrode. These electrodes are placed into copper sulphate solution. When the circuit is pushed, the atoms of copper in the impure copper are changed into positive copper ions and travel to the negative electrode. Here they are changed back into neutral copper atoms and they form around the CATHODE. The cathode increases size in the reaction, and the impure anode reduces in size, finally leaving only anode slime. Phytomining and Bioleaching For low grade ores Rocks with low metal content These are new metal extraction methods for low grade ores. These are ORES with very little metal content and so traditional mining methods would result in BIGGER Quarries and most waste rock to dispose of. Plants absorb the metal into their roots and then they are burnt to leave a metal rich ash. Electrolysis then removes the metal from the ash. The burning can also provide energy. Bioleaching uses bacteria to pull out metal from ores to produce a copper rich solution. The use of scrap iron to displace copper is also important here Why should we recycle? Recycling conserves resources like ores and fuels, making them last much longer. It also reduces energy use and so reduces CO2 production and potential global warming. The public must be persuaded to do this however to make it an efficient process.
AQA C1 Crude Oil &Hydrocarbons Making Oil useful Fractional Distillation Crude oil is a major source of hydrocarbons. On it s own it is not useful but with FRACTIONAL DISTILLATION the different sized hydrocarbons can be separated and then used as either fuels or raw materials for roads or medicines. The column is temperature gradient - Hot at the bottom and cold at the top. The oil is heated to approx 350 C. This causes the majority of the small and medium hydrocarbons molecules to evaporate and rise up the column. The large molecules can not evaporate due to their bigger size. As the molecules rise up they start to cool down and eventually when they hit their boiling point, they will condense back to a liquid and be separated. The smaller molecules can get to the top before they condense as they have the lowest boiling points. What are Alkanes? Hydrocarbons are compounds made from only hydrogen and carbon atoms. In C1, you need to know about 2 families ALKANES and ALKENES. ALKANES are unsaturated molecules as they have only carbon carbon single covalent bonds. All their names end in ane. The number of carbon atoms is linked to the number of hydrogens by this formula CnH2n+2 Combustion of Hydrocarbons Hydrocarbons are the main fuels of the modern world. When they burn they react with oxygen in an EXOTHERMIC reaction to release energy. With PLENTY of oxygen, hydrocarbons produce carbon dioxide and water. When the OXYGEN is limited, CARBON MONOXIDE is made which is TOXIC Know how these gases are made CO CO2 NO2 SO2