AQA Chemistry A level with complete solutions

What is the relative mass and charge on a proton? Mass 1 charge +1 What is the relative mass and charge on a neutron? Mass 1 Charge 0 What is the relative mass and charge on an electron? Mass 1/2000 Charge -1 What is the mass number? The total number of protons and neutrons in the nucleus of an atom What is the Atomic (proton) number? This is the number of protons in the nucleus of an atom and is used to identify an element What are Ions? 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? Isotopes of an element are atoms with the same number of protons but different numbers of neutrons describe Thomson's model of the atom. 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? 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? 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? 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? 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? 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? 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 relative atomic mass = isotopic masses x percentages/total percentage What is relative molecular mass? 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? Number of moles = mass(g)/ mass of one mole (mol) What are the 5 stages in mass spectrometery? vaporisation, ionisation, acceleration, deflection, and detection What happens during the vaporisation stage of mass spectrometry? The sample is turned into a gas using an electrical heater in a vacuum. What happens during the ionisation stage of mass spectrometry? 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? 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? 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? 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? X(g) => X+ = e-