2 - atoms, ions and compounds

• Isotope


  Isotopes are atoms of the same element with different numbers of neutrons and different masses.
• How do different isotopes of the same element react?


  Chemical reactions involve electrons surrounding the nucleus.

  
  

  Different isotopes of the same element have the same number of electrons. The number of neutrons has no effect on reactions of an element. Different isotopes therefore react the same way.
• How do physical properties of isotopes of the same element differ?


  Higher mass isotopes (those with more neutrons) have a higher melting point, boiling point, and density.
• Cation


  A positively charged ion.
• Anion


  A negatively charged ion.
• Relative isotopic mass 


  The mass of one isotope compared to one-twelfth of the mass of one atom of carbon-12
• Relative atomic mass

  The weighted mean mass of an atom of an element compared to one-twelfth of the mass of an atom of carbon-12.
• What is a mass spectrometer used for


  The mass spectrometer is used to determine the percentage abundances of the isotopes in a sample.
• What are polyatomic ions?


  Ions containing more than one element bonded together . E.g. nitrate NO₃⁻
• +1 ions


  Hydrogen, silver, gold, ammonium
• +2 ions


  Zinc, copper (II), iron (II), tin, lead
• +3 ions


  Iron (III)
• -3 ions


  Phosphate
• -2 ions


  Carbonate, sulfate
• -1 ions


  Nitrate, hydroxide
• Relative molecular mass


  The average mass of a molecule compared to one-twelfth of the mass of one atom of carbon-12.
• Ammonium ion

  NH4^+
• Carbonate ion

  CO3^2-
• Chromate ion


  CrO4^2−
• Dichromate ion


  Cr2O7^2−
• Hydrogen carbonate ion (bicarbonate ion)


  HCO3^−
• Hydroxide ion


  OH^-
• Nitrate ion


  NO3^−
• Nitrite ion


  NO2^-
• Permanganate ion


  MnO4^−
• Phosphate ion


  PO4^3−
• Sulfate ion


  SO4^2−
• Sulfite ion


  SO3^2−