2.11, 2.12 and 2.13

• Atom


  Made of protons and neutrons in the nucleus, with negative electrons orbiting in shells
• Proton


  • Relative charge of +1, relative mass of 1
• Neutron


  • Relative charge of 0, relative mass of 1
• Electron


  • Relative charge of -1, relative mass of 1/2000
• The number of protons equals the number of electrons in atoms
• To find the number of neutrons, subtract the atomic number from the mass number
• Ion


  Atom that has lost or gained electrons, so has a different number of electrons and protons
• Ions


  • Oxygen ion with 8 protons, 8 neutrons, and 10 electrons (charge of -2)
  • Sodium ion with 11 protons, 12 neutrons, and 10 electrons (charge of +1)
• Isotope


  Atoms of the same element with the same number of protons but different numbers of neutrons
• Isotopes of carbon


  • Carbon-12 (6 protons, 6 neutrons)
  • Carbon-13 (6 protons, 7 neutrons)
  • Carbon-14 (6 protons, 8 neutrons)
• Relative atomic mass (Ar)


  Weighted mean mass of an atom of an element compared to 1/12 of the mass of a carbon-12 atom
• Relative isotopic mass


  Mass of an atom of an isotope compared to 1/12 of the mass of a carbon-12 atom
• Relative molecular mass


  Mean mass of a molecule compared to 1/12 of the mass of a carbon-12 atom
• Mass spectrometry


  Technique to measure the mass-to-charge ratio (m/z) and relative abundance of isotopes in a sample
• Using mass spectrometry data

  1. Find m/z ratio

  2. Determine relative abundance of each isotope

  3. Calculate relative atomic mass by multiplying mass by abundance and summing
• The relative atomic mass calculated from mass spectrometry data can be used to identify the element on the periodic table
• Ions are created when electrons are transferred from one atom to another
• Forming compounds


  1. Ions attract each other

  2. Form ionic bond
• Ions formed by groups

  • Group 1 form 1+ ions
  • Group 2 form 2+ ions
  • Group 3 form 3+ ions
  • Group 4 don't easily lose/gain electrons
  • Group 5 form 3- ions
  • Group 6 form 2- ions
  • Group 7 form 1- ions
• Molecular ions


  • Hydroxide OH-
  • Nitrate NO3-
  • Ammonium NH4+
  • Sulfate SO4 2-
  • Carbonate CO3 2-
• Ionic compound formula


  Swap charges, drop charges, combine and simplify
• Ionic compounds


  • Compounds formed by the transfer of electrons between metals and non-metals
• Salts


  • Can be hydrated with water (water of crystallization)
  • Can be anhydrous (without water)
• Water is a polar molecule
• Water interacts with ionic compounds

  Oxygen attracted to positive ions, hydrogen attracted to negative ions
• Water of crystallization


  Water molecules existing within the crystal structure of a salt
• Determining water of crystallization

  1. Heat salt to remove water

  2. Mass of anhydrous salt left gives water of crystallization
• Ionic equation


  Shows ions formed in solution and which particles are reacting
• In neutralization reactions, H+ ions come from acid, OH- ions come from base, and they form water
• Spectator ions don't participate in the reaction
• Mole


  Unit to measure amount of substance, contains 6.02x10^23 particles (Avogadro's number)
• Calculating number of particles from moles

  Multiply Avogadro's number by moles
• Moles, mass, and molecular/atomic mass

  Number of moles = mass / molecular or atomic mass
• The number of particles can be calculated using a formula
• Calculating number of moles

  Mass in grams / Atomic/Molecular mass
• If you have any two of mass, moles, or atomic/molecular mass, you can use the equation to calculate the third
• Concentration


  Mol/dm^3
• Volume


  Measured in dm^3
• Calculating number of moles in a solution

  Concentration x Volume
• Ideal gas equation


  PV = nRT