chemistry formulas

  • Created by: Najma
  • Created on: 19-12-12 10:30

Non-Metals form negative ions





whilst metals form positice ions

eg: Mg2+


  • N= VC /1000
  • C= 1000N/V
  • N=m/Mr
  • m=N/Mr
  • definitions
  • Definitions

    • Relative atomic mass ; This is the mass of an atom compared to 1/12 of the mass of an atom of carbon 12. Where carbon is exactly 12.
    • Relative isotopic mass ; The mass of an isotope compared to 1/12 the mass of a carbon 12 atom, where carbon is exactly 12.
    • Relative formula mass ; The mass of a compound compared to 1/12 the mass of a carbon 12 atom, where carbon is exactly 12.
    • The mole is a unit of measurement used in chemistry to allow us to weigh out the correct number of particles, (ions, electrons, compounds etc ... for a chemiscal reaction)
    • Ionisation energy ; Is the energy required to remove 1 mole of electrons from1 mole of gaseous atoms to form 1 mole of gaseous ions.
    • Periodicity ; A graph has this when a repeated pattern is apparent... E.g... First Ionisation energies.
    • Electron ; Cloud of negative charge, it fills a volume in space called an orbital.
    • Orbital ; A space of volume
      • Explaining Electrons

    • The electon configuration is now using S,P,D and F's...

      • E.g Hydrogen would be 1s1... :)
      • So it goes up like... :
      • 1s2, 2s2, 2p6,3s2,3p6,4s2,3d10,4p6...
      • The 4s2 gets filled before the 3d10 because it is easier to fill the 4s2.... after the 4th s - orbital is completed, it goes back to filling up the 3d- or
      • Density = Mass/Volume

        Moles = Mass/RMM

        Atoms = Mass/RMM x (6.02x10^23)

        % Yeild = Actual/Theoretical x 100

        To get Theoretical:

        • Balance Equation
        • Find Moles
        • Find limiting reagent
        • (Solid) Mass/RMM
        • (Gas/Liquid) [Mass/Volume]/RMM
        • Using Moles, find Mass in Grams.
        • Mass concentration=

          • Mass (dm³) / Volume 
            • Mole concentration=

          Number of moles / Volume (dm³)

          Formulae and Equations

          Here are the basic formulae:

          No. of moles = mass / molar mass

          Volume = No. of moles x 24000

          Concentration = No. of moles / Volume



          You can work out moles if you have the mass and the molar mass using the simple equation above. 

          You can also work out mass and molar mass using this equation.



          There are a number of volume calculations.


          1. Sheldon has 4 moles of oxygen. What volume of oxygen does she have?

          Volume = moles x 24000

          4 x 24000 = 96000cm3 = 96dm3

          2. Raj has 40g of methane gas. What volume does she have?

          Moles = mass / molar mass

          40 / 16 = 2.5 moles

          Volume = moles x 24000

          2.5 x 24000 = 60000cm3 = 60dm3

          3. Howard has 400cm3 of nitrogen. What mass of nitrogen does he have?

          Moles = Volume…




Great help! Ehm, Sheldon and Raj are a "she"?

Thank you;)



Big bang theory characters should be used in exam questions!!!



ross rachel XD loving this ! f.r.i.e.n.d.s yeahhh



ross rachel XD loving this ! f.r.i.e.n.d.s yeahhh



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