chemistry formulas
 Created by: Najma
 Created on: 191212 10:30
NonMetals form negative ions
Cl^{}
Br^{}
O^{2}
S^{2}
whilst metals form positice ions
eg: Mg2+
Formulas
 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=

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

Moles
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.

Volume
There are a number of volume calculations.
Examples:
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…
 Mass (dm³) / Volume
Comments