Spectrometer

1. Ionisation enery is the energy needed to remove 1 mole of electrons from 1 mole of 1 mole of atom in it gaseous state 
2. First ionisation s energy needed to remove1 electron from a neutral atom 

Equation (= + at the top) 

1st IE   atom(g) ----> atom (g) + e- 2nd IE     atom*(g) ---> atom2* (g) + e-

eg.       Na(g) ----> na*(g) + e-

ionisation energy decreases s you go down the group, this is because;

• group tells you the number of electrons on the outer shell, priod tells you how many shells 
• as you go down the groups the eectrons gets furter away from the nuclers o easier to ionise 
• as you go down the group the period increases, therefore more shells acting as elctron shielding

why is it that as we go from magnesium to aluminium the ionisation energy decreases?

• because the outer electron for magnesium is in 3s(2) ortibal and the orbital is full 
• whereas the outer electron for aluminium is in 3p(1) orbital and is not full(only 1 electron) so its easier to lose.

why is it that a the ionisation energy for phosphorus is higher that sulfur ?

• because in phosphrus each of the 3p orbital contain just 1 electron so no repulsion 
• whereas in sulfur 1 of the 3p orbital has 2 electron so there's repusion between the two electrons

                                                                          average mass (g) element

•            relative atomic mass (Ar) =                       --------------------  = Ar

                                                                           mass of atom 

                    eg  H2O (H=1.0,  O=16.0,)  

                          H20 = (2X1.0) +16.0 = 18.0 Ar

                                                                               average mass (g) molecule

•            relative molecular mass (Ar) =                     --------------------  = Mr

                                                                                 mass of atom 

                           eg  H2O (H=1.0,  O=16.0,)  

                     H20 = (2X1.0) +16.0 = 18.0 Mr

• Avogadro constant is the number of atom in 12g of C-12.          6.022x10 (to the power 23)

•                       # of Moles =  mass (gram) given

                                                             ------------------      = mol

                                               mass of atom (periodic table)

                                        eg how many moles in 64.2g f sulfur (S)? Ar S = 32.1 

                                          64.2g

                                                       -------    = 2.00 mol

                                          32.1  

•                      The ideal GAS equation:   PV= nRT   Pressure Pa,Volume M(3),n=mole,temp K +273 ,R=8.31

Eg temp = 20.0 C (293.0 K), Pressure = 100,000Pa, and n = 1 or 1 mole of gas, R = 8.31

V? = nRT/P    V= 1x8.31x293.0

                        -------------- =

                           100,000 

Concentration = moles x 1000

                    ---------------

                   volume