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AQA CHEMISTRY A LEVEL QUESTIONS AND ANSWERS WITH SOLUTIONS 2024
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AQA CHEMISTRY A LEVEL QUESTIONS AND ANSWERS WITH SOLUTIONS 2024
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AQA CHEMISTRY A LEVEL QUESTIONS AND ANSWERS WITH SOLUTIONS 2024 What is the relative mass and charge on a proton? - ANSWER Mass 1 charge +1 What is the relative mass and charge on a neutron? - ANSWER Mass 1 Charge 0 What is the relative mass and charge on an electron? - ANSWER Mass 1/2000 Charge -1 What is the mass number? - ANSWER The total number of protons and neutrons in the nucleus of an atom What is the Atomic (proton) number? - ANSWER This is the number of protons in the nucleus of an atom and is used to identify an element What are Ions? - ANSWER Ion have different numbers of protons and electrons. Negative ions have more electrons than protons and positive ions have fewer electrons than protons. What are isotopes? - ANSWER Isotopes of an element are atoms with the same number of protons but different numbers of neutrons describe Thomson's model of the atom. - ANSWER Thomson's model of the atom was like a 'plum pudding' with a positively charged pudding (solid sphere) that contained negatively charged particles (electrons). What was found in Rutherford's gold foil experiment? - ANSWER When alpha particles were fired at a thin gold sheet, most of them passed straight through with a very small number deflected straight back. What was Rutherford's new nuclear model for the atom? - ANSWER A tiny positively charged nucleus at the centre, surrounded by a cloud of negative electrons. Most of the atom is empty space. What did Bohr's atom model show? - ANSWER Electrons only exist in fixed orbits and not anywhere in between. Each Shell has a fixed energy. When an electron moves between shells, electromagnetic radiation is emitted or absorbed. Because the energy of the shells is fixed, the radiation will have a fixed energy. What difference is found between the original Bohr atom model and the refined Bohr model? - ANSWER Scientists discovered that not all electrons in a shell have the same energy, so it was refined to include sub shell's. What is relative atomic mass? - ANSWER The average mass of an atom of an element compared to one twelfth of the mass of an atom of carbon 12. What is relative isotopic mass? - ANSWER Relative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of Carbon -12 is exactly 12. Calculating relative atomic mass - ANSWER relative atomic mass = isotopic masses x percentages/total percentage What is relative molecular mass? - ANSWER The average mass of an entity compared to one twelfth of the mass of an atom of carbon 12. What is the equation used to calculate the number of moles of any substance? - ANSWER Number of moles = mass(g)/ mass of one mole (mol) What are the 5 stages in mass spectrometery? - ANSWER vaporisation, ionisation, acceleration, deflection, and detection What happens during the vaporisation stage of mass spectrometry? - ANSWER The sample is turned into a gas using an electrical heater in a vacuum. What happens during the ionisation stage of mass spectrometry? - ANSWER An electron gun fires a beam of high energy electrons which bombards the gaseous particles, knocking off electrons leaving a positive ion What happens during the acceleration stage of mass spectrometry? - ANSWER The positive ions are attracted by negatively charged plates in an electric field which accelerates the ions and focuses the beam. What happens during the deflection stage of mass spectrometry? - ANSWER The fast moving ions pas into a string magnetic field, deflecting the ions into a curved path. The degree of deflection depends on the Mass/charge ratio (m/z). Ions with with a high m/ z ratio are deflected the least (they're heavier). The strength of the magnet is gradually increased so that ions with different m/z ratios are deflected towards the detector. What happens during the detection stage of mass spectrometry? - ANSWER The positive ions hit an electrically charged plate/ the current produced is then amplified and recorded as a 'peak'. Each peak is a measure of the relative abundance of each ion. What is the general ionisation equation? - ANSWER X(g) => X+ = e - What does a mass spectrum chart show? - ANSWER Each line represents a different isotope of an element. the height of each peak gives the relative isotopic abundance (the amount of it). For a molecular substance the peak with the greatest m/z ratio correspo nds to the Mr. What are the steps in calculating relative atomic mass? - ANSWER Step 1: For each peak multiply the relative isotopic abundance by the relative isotopic mass. Step 2: Add up these totals. Step 3: Divide by 100 How many orbitals do each -sub shell contain? - ANSWER s - 1 p - 3 d - 5 f - 7 What are four rules for electronic arrangement notation? - ANSWER 1: Each principle and subsidiary level fills up before the next one 2: When the 3p energy level is full, the 4s level fills before the 3d 3: When an atom or ion has 3d electrons, the 4s is written after the 3d 4: Atoms that have 3d electrons always lose the 4s electrons first while forming ions What is the first ionisation energy? - ANSWER The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions. How does nuclear charge affect ioniation energy? - ANSWER The more protons that are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons How does distance from the nucleus affect ionisation energy? - ANSWER Attraction falls off very rapidly with distance. An electron close to the nucleus will be much more strongly attracted than one further away. How does shielding affect ionisation energy? - ANSWER As the number of electrons between the outer electrons and the nucleus increases, the outer electrons feel less attraction towards the nuclear charge. This lessening pull of the nucleus by inner shells of electrons is called shielding. What is the second ionisation energy? - ANSWER The second ionisation energy is the energy needed to remove an electron from each ion in 1 mole of gaseous 1+ ions. What is the trend in ionisation energy down group 2? - ANSWER First ionisation energy decreases down Group 2. This provided evidence that electron shells really do exist. What is the trend in ionisation energy across periods? - ANSWER As you move across a period the general trend is for the ionisation energy to increase, it gets harder to remove an electron. This is because the number of protons is increasing which means a stronger nuclear attraction.The benefits of buying summaries with Stuvia:
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