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