Revision Notes - Unit 1 AQA Chemistry A-level.

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AQA AS level Unit 1 Chemistry notes by Luna Hu Atomic structure Particle Mass (kg) Relative mass Charge (c) Relative charge Proton 1.67x10-27 1 1.6x10-19 +1 Neutron 1.675x10-27 1 0 0 Electron 9.... 11x10-31 1/1840 -1.6x10-19 -1 Relative atomic mass: Average weighted mass of an atom of an element relative to 1/12 mass of an atom of C12  This is why mass of C12 is exactly 12.00000 – it is the reference isotope. Relative molecular mass: Mass of a molecule relative to 1/12th mass of C12 atom. [Relative formula mass for ionic] Isotope: atoms with the same number of protons but different number of neutrons.  Isotopes have similar chemical properties as they have the same electron number and configuration, which determines chemical property. Mass spectrometer: - Find out relative atomic mass, relative molecular mass, relative isotopic abundance, and molecular structure and to identify elements. Condition: vacuum – no obstruction, lower pressure (thus less heat required to vaporize sample) and to clean out sample. 1. Vaporization – Sample is vaporized so there is no attraction between the atoms. 2. Ionization – high-energy electrons from an electron gun knocks out electron(s) thus ionizes gaseous sample (in order for the following events to happen) 3. Acceleration – negatively charged plates attract the ionized sample, forcing the sample through slits, forming a Cation beam. 4. Deflection – The Cation beam is deflected by the magnetic field, as it is electrically charged. Extent of deflection depends on the m/z ratio  this ensures 1 isotope detected each time. 5. Detection – The sample lands on negatively charged detection plate, accepts electron(s), and a current passes. The current is proportional to the abundance of the isotope. (Small peaks far away from main peaks are caused by 2+ ions in which 2 electrons have been removed)  Generate a mass spectrum showing the relative abundance against m/z ratio [Show More]

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