AS-level AQA Chemistry questions and answers

AS-level AQA Chemistry questions and answers What is the charge of a proton? - ANSWERS +1 What is the charge of a neutron? - ANSWERS 0 What is the charge of an electron? - ANSWERS -1 What is the mass of a proton? - ANSWERS 1 What is the mass of a neutron? - ANSWERS 1 What is the mass of an electron? - ANSWERS 1/1800 What is an isotope? - ANSWERS Isotopes of an element are atoms with the same number of protons but different numbers of neutrons. Why do isotopes of an element all have the same chemical properties? - ANSWERS This is because chemical properties are decided by the number and arrangements of electrons and all isotopes of an element have the same number of electrons. Why do isotopes of an element have different physical properties? - ANSWERS This is because physical properties are decided by the mass number and isotopes of an element have different mass numbers. What is the first stage in time of flight mass spectrometry and what are the 2 ways it can occur? - ANSWERS 1. Electron spray ionisation 2.Electron impact ionisation What is electron spray ionisation? - ANSWERS The sample is dissolved and pushed through a small nozzle at high pressure. A high voltage is applied to it causing each particle to gain a + ion so that the gas is made up of positive ions. What is electron impact ionisation? - ANSWERS The sample is vaporised and an electron gun is used to fire high energy electrons which knocks of 1 electron of each particle so they become positive ions. What is the second stage in time of flight mass spectrometry? - ANSWERS Acceleration What happens in the acceleration stage of time of flight mass spectrometry? - ANSWERS The positively charged ions are accelerated by an electric field so that they all have the same kinetic energy which means that the lighter ions will move faster than the heavier ions. What is the third stage in time of flight mass spectrometry? - ANSWERS Ion drift What happens in the ion drift stage of time of flight mass spectrometry? - ANSWERS The ions enter a region with no electric field, so they just drift through it. Lighter ions will drift through faster than heavier ions. What is the final stage of time of flight mass spectrometry? - ANSWERS Detection What happens in the detection stage of time of flight mass spectrometry? - ANSWERS Because ions have a lower mass/charge ratio travel at a higher speed in the drift region, they reach the detector in less time than ions with a higher mass/charge ratio. The detector detects charged particles and a mass spectrum is produced. What is the electronic configuration of calcium? - ANSWERS 1s2,2s2,2p6,3s2,3p6,4s2 What is the electronic configuration of chromium? - ANSWERS 1s2,2s2,2p6,3s2,3p6,3d5,4s1 What is the first ionisation energy? - ANSWERS The first ionisation energy needed to remove one electron from each atom in 1 mole of gaseous atoms to form 1 mole of +1 gaseous ion.. How does nuclear charge affect ionisation energy? - ANSWERS More protons means more positively charged means the stronger the attraction for electrons. How does distance from the nucleus affect ionisation energy? - ANSWERS The closer the electron is to the nucleus, the stronger the attraction. How does shielding affect ionisation energy? - ANSWERS As the number of electrons between outer electrons and the nucleus increases, the outer electron feels less attraction towards the nuclear charge. What is the trend in ionisation energy down a group? - ANSWERS The first ionisation energy down a group has a general decrease because down a group each element has an extra electron shell compared to the one above so the extra inner shells will shield the outer electrons from the nucleus attraction. What is the trend in ionisation energy across a period? - ANSWERS The first ionisation energy across a period has a general increase because it gets harder to remove outer shell electrons. What is the definition of relative atomic mass (Ar)? - ANSWERS The relative atomic mass is the average mass of an atom of an element on a scale where an atom of carbon-12 is 12. What is the definition of relative molecular mass (Mr)? - ANSWERS The relative molecular mass is the average mass of a molecule on a scale where an atom of carbon12 is 12. What is the Avogadros Constant? - ANSWERS The number of particles in a mole which is equivalent to 6.02 x 10^23. What is an equation for number of moles involving mass and Mr? - ANSWERS number of moles = mass / Mr What is an equation for number of moles involving concentration and volume? - ANSWERS number of moles = concentration x volume What is an equation for number of particles involving number of moles and Avogadros constant? - ANSWERS number of particles = number of moles x Avogadros constant What is the Ideal Gas Equation? - ANSWERS PV = nRT What is P in regards to the Ideal Gas Equation and wh