Module 2

• Atomic Number


  the number of protons in the nucleus of an atom
• Bohr Model


  describes an atom as a small dense nucleus with electrons orbiting around the nucleus. Model explains different periodic properties of atoms.

  
• Electron


  a negatively charged subatomic particle which orbits the nucleus at various energy levels The relative mass of an electron is 1/1836
• lon


  a charged atom or molecule
• Isotopes


  atoms of the same element with the same number of protons and electrons but different numbers of neutronsIsotopes of an element have different masses
• Mass Number


  the total number of protons and neutrons in the nucleus of an atom
• Mass Spectrometry


  an instrument which gives accurate information about relative isotopic mass and the relative abundance of isotopes
• Neutron


  a neutral subatomic particle found in the nucleus of an atom relative mass of a neutron = 1
• Proton


  a positively charged subatomic particle found in the nucleus of an atom The relative mass of a proton = 1
• Relative Abundance


  the amount of one substance compared with another
• Relative Atomic Mass


  the weighted mean mass of an atom compared with 1 / 12th mass of an atom of carbon - 12
• Relative Isotopic Mass


  the mass of an atom of an isotope compared with 1 / 12th mass of an atom of carbon - 12
• Relative Formula Mass


  the mass of the formula unit of a compound with a giant structure e.g : NaCl has a relative formula mass of 58.44 g mol - ¹ .
• Relative Molecular Mass (Mr)


  the mass of a simple molecule
• Ammonium ion


  an ion with the formula :

  
• Carbonate


  an ion with the formula :

  
• Hydroxide


  an ion with the formula :

  
• Ionic Compound


  a compound which is made up of oppositely charged ions that are held together by electrostatic forces
• Nitrate


  an ion with the formula :

  
• Silver ion


  has the formula :

  
• State symbols


  symbols within a chemical equation which indicate the state of each compound under the reaction conditions ● (g) gaseous ● (l) liquid ● (s) solid ● (aq) aqueous
• Sulfate


  an ion with the formula :

  
• Zinc ion


  has the formula :

  
• Amount of substance

  the quantity that has moles as its units used as a way of counting atoms The amount of substance can be calculated using :● mass ( n = m / M ) ● gas volumes ( n = pV / ( RT )) ● solution volume and concentration ( n = C × V )
• Anhydrous


  a crystalline compound containing no water
• Atom Economy

  measure of the amount of starting materials that end up as useful products A high atom economy means a process is more sustainable as there is less waste produced

  
• Avogadro Constant


  the number of particles per mole of substance ( 6.02 x 10²³ mol - ¹ )

  
• Composition by mass


  the relative mass of each element in a compound
• Empirical Formula


  the simplest whole number ratio of atoms of each element present in a compound
• Hydrated

  a crystalline compound that contains water
• Ideal Gas


  a gas which has molecules that occupy negligible space with no interactions between them The ideal gas equation :

  
• Molar Gas Volume


  the volume of 1 mole of gas ( dm³ mol ‐ ¹ )

  
• Concentration of a solution


  how many moles/grams of something are dissolves per 1 dm³ of solution ( mol dm-³ / g dm-³ )

  
• Molar Mass

  mass per mole of a substance ( g mol - ¹ )
• Mole (mol)


  the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of carbon - 12 isotope

  
• Molecular Formula


  the number and type of atoms of each element in a molecule
• Percentage Yield

  percentage ratio of the actual yield of product from a reaction compared with the theoretical yield

  
• Relative Molecular Mass

  the average mass of one molecule of an element or compound compared to 1 / 12th the mass of an atom of carbon - 12
• Stoichiometry


  the relative quantities of substances in a reaction
• Water of Crystallisation


  water molecules that form part of the crystalline structure of a compound