Module 2

• Proton


  Charge +1, relative mass 1
• Neutron


  Charge 0, mass 2.1
• Electron

  Charge -1, relative mass 1/2000
• Atom


  Held together by electrostatic attraction between the nucleus and negative electrons
• Ion


  Molecules formed when atoms gain or lose electrons, causing them to become charged
• Atomic number


  Number of protons
• Mass number


  Number of protons + number of neutrons
• Neutral atom


  Has the same number of protons and electrons
• Cation


  Positively charged ion
• Anion

  Negatively charged ion
• Isotopes


  Atoms of the same element with the same number of protons and electrons but a different number of neutrons, resulting in different mass numbers and physical properties
• Atomic mass unit (u)

  The standard mass for atoms, defined as 1/12 the mass of a carbon-12 atom
• Relative isotopic mass


  The mass of an isotope relative to 1/12 of a carbon-12 atom
• Relative atomic mass


  The weighted mean mass of an atom relative to 1/12 of a carbon-12 atom
• Mass spectrometry


  Sample vapourised, ionised, ions accelerated and detected at mass-to-charge ratio (m/z)
• Relative molecular mass


  The mass of a chemical compound relative to the mass of a carbon-12 atom
• Ionic compound


  Compound formed by the bonding of a metal and a non-metal, electrically neutral
• Ionic compounds


  • Silver (I) Ag+
  • Ammonia NH4+
  • Zinc (II) Zn2+
  • Nitrate NO3-
  • Hydroxide OH-
  • Sulfate SO42-
  • Carbonate CO32-
  • Hydrogen carbonate HCO3-
  • Phosphate PO43-
• Ionic equation


  Shows only the ions or particles taking part in a reaction, excluding spectator ions
• Avogadro constant, NA, is the number of particles equivalent to the relative mass of a substance
• Mole (mol)


  The amount of substance containing the same number of particles as there are atoms in 12 grams of carbon-12
• Molar gas volume


  The volume occupied by one mole of any gas at room temperature and pressure, 24 dm3
• Molecular formula


  The number and type of each atom in a molecule
• Empirical formula


  The simplest whole number ratio of elements present in one molecule of the compound
• Hydrated compound


  A compound that has water as part of its crystal structure
• Water of crystallisation


  The water that is part of the crystal structure of a hydrated compound
• Anhydrous

  A compound without any water of crystallisation
• Determining degree of hydration


  Heating the hydrated salt until constant mass, then calculating the mass of water lost
• Concentration


  The amount of solute dissolved in a solvent to make 1 dm3 of solution
• Ideal gas


  • Molecules move fast and randomly, have negligible volume, and do not attract or repel each other
• As temperature increases


  Particle kinetic energy increases, leading to more frequent collisions with container walls and increased pressure, so volume must increase
• Percentage yield


  Actual yield / Theoretical yield x 100
• Atom economy

  Mass of desired product / Mass of all reactants x 100
• Reactions may not go to completion due to side reactions, incomplete conversion of reactants, or loss of products during separation and purification
• High percentage yield suggests an effective process for converting reactants to products, but does not account for waste products
• Low atom economy indicates more waste is produced
• Choosing a reaction pathway with fewer steps, reducing/preventing waste, and reducing energy demand is better for the environment (green chemistry) and reduces production costs
• Higher atom economy means less waste is produced
• Strong acid


  Fully dissociates in solution
• Strong base


  Fully dissociates in solution