Chemistry - Key definitions and formulas

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

• 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

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- orbital