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6 Cards in this Set
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What is first ionisation energy? What type of process is this reaction? The lower the ionisation energy... What are the factors affecting ionisation energy? A higher ionisation energy means... |
It is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous +1 ions. It is an endothermic process. The easier it is to form an ion. Nuclear charger - the more protons there are in the nucleus the more +vely charged the nucleus is and the stronger the attraction for the electrons. Distance from nucleus - attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attracted than one further away. Shielding - as the number of electrons between the outer electrons and the nucleus increases, the outer electrons feel less attraction towards the nuclear charge. This is shielding. Theres a high attraction between the electron and the nucleus and so more energy is needed to remove the electron. |
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Every time you remove an electron there is.. What is the definition for the second ionisation? What is the nth ionisation energy? What does a graph of ionisation energies show? What happens within each shell? When do the big jumps occur? What do ionisation energy graphs show? |
A successive ionisation energy. It is the energy needed to remove 1 electron from each ion in 1 mole of gaseous +1 ions to form 1 mole of gaseous 2+ ions. X(n-1) > X(n+) + e-. Evidence for shell structure of atoms. Successive ionisation energies increase. Because electrons are being removed from an increasingly positive ion, this means that there is less repulsion amongst the remaining electrons so they are held more strongly by the nucleus. When a new shell is broken into - this is because an electron is being removed from a shell close to the nucleus. What group of periodic table the element belongs to and also the periodic structure of elements. |
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As you go down a group.. As you go across a period.. Which two examples must you know about? What happens down group 2? Period 3? What happens between group 2 and group 3? Mg - 1s2 2s2 2p6 3s2 Al - 1s2 2s2 2p6 3s2 3p1 What do patterns in ionisation energies show? |
The ionisation energies decrease. They increase. As you go down group 2 and across period 3. Group 2 shows that ionisation decreases with more shells. This is due to shielding and making the outer electrons further away. Period 3 shows that ionisation energies increase as you move across this is due to a stronger nuclear attraction. There is little extra shielding effect or extra distance to lessen the attraction. Specifically Mg and Al. Al - outer electron is in orbital 3p rather than a 3s. The 3p has a slightly higher ionisation energy and so has additional shielding and the 3p orbital has a higher energy than 3s so is further from the nucleus. These two factors are enough to override the increased nuclear charge. Provide evidence for the theory of electron sub shells. |
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What is the drop between group 5 and 6 caused by? P - 1s2 2s2 2p6 3s2 3p3 S 1s2 2s2 2p6 3s2 3p4 How many particles does 1 mole contain? Formula? 1 dm3? What does the ideal gas equation allow you to do? What does an ionic equation involve? What must you make sure with an ionic equation? Calculate the mass of iron oxide if 27.9g of iron is burnt in air. |
The shielding is identical but in phosphorus' case, the electron is being removed from a singly occupied orbital. But the sulphur is being removed from an orbital containing two electrons. The repulsion between the two electrons means that they are easier to remove. 6.02 x 10^23 atoms. Number of particles = number of moles x avagadro. 1 litre. The number of moles in a certain volume of gas. Only the reacting particles and the products they form. That the charges balance - equal 0. Balanced equation 4Fe + 3O2 > 2Fe2O3. Number of moles in Fe - 27.9/55.8. Mr of Fe2O3= 159.6 Mass of Fe2O3 produced = 0.250 x 159.6 = 39.9g |
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What volume of gas, in dm3, is produced when 15.0g of sodium reacts with excess water at a temp of 25 degrees c and a pressure of 100 kPa? How in terms of burette etc would you carry out a titration? In terms of accuracy what must you do? Empirical formula? Molecular formula? When a hydrocarbon is burnt in excess oxygen, 4.40g of carbon dioxide and 1.80g of water are made. What is the empirical formula of the hydrocarbon? |
Mr of Na = 23.0 so moles = 15/23 = 0.652 moles. 2 moles of Na produces 1 mole of H2 so 0.625/2 = 0.326 moles of hydrogen. volume = 8.07 dm3. Use a pipette to measure out a set volume of the solution that you want to know the concentration of. Put it in a flask. Add a few drops of an appropriate indicator to the flask. Then fill a burette with a standard solution and use a funnel, always do this below eye level to avoid any splashing. Do a rough titration to get an idea where the end point is, then do an accurate titration and then repeat until you get concordant results. It gives the simples whole number ratio of atoms of each element in a compound. Gives the actual numbers of atoms of each element in a compound. No of moles of CO2 = mass/mr 4.40/44 = 0.100 moles. 1 moles of CO2 contains 1 mole of carbon atoms, so the original hydrocarbon must have contained 0.100 moles of carbon atoms. No of moles of H20 1.80/18 = 0.100 moles. 1 mole of H2O contains 2 moles of hydrogen atoms so the original must have contained 0.200 moles of hydrogen atoms. Ratio 0.100:0.200 now divide by the smallest - 0.100 times 1:2 so the formula must be CH2. |
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What is theoretical yield? 1.40g of iron fillings reacts with ammonia and sulphuric acid to make hydrated ammonium iron (II) sulfate. Calculate the theoretical yield of the reaction. 0.475g of CH3Br reacts with excess NaOH in the reaction. 0.153g of CH3OH is produced. What is the percentage yield? |
It is the mass of the product that should be formed in a chemical reaction. You started off with 1.40g of iron fillings and this has an mr of 55.8 moles = 1.40/55.8 = 0.0251. From the equation the stoichiometry is 1:1. Mr of product is 392.0 so theoretical yield = 0.0251 x 392.0 = 9.84g. 5.22/9.84 x 100 = 53%. Moles of CH3Br 0.475/94.9 = 0.0051 mol. Mr of CH3OH = 32 theoretical yield = 0.00501 x 32 = 0.160g. o.153g/0.160g x 100 = 95.6% |
