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General Equations and Definitions
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  • Atomic Masses = the number of protons and neutrons
  • Atomic Number = number of protons and therefore also the number electrons
  • Electron Shielding = This is where electrons in the inner shells of a atom stop the full charge of the nucleus effect electrons outside that shell, e.g. if a shell has 6 electrons it will reduce the effective nuclear charge by 6+.
  • Enthalpy = This is the energy change of a substance per mole.

 

Particles in the atom

Charge in Coulombs

Mass in Kg

Relative Charge

Relative mass

P proton

1.602

´ 10 – 9

1.672 

 ´ 10- 27

         +1

          1

N neutron

0

1.675

´ 10 -27

            0

          1

E electron

1.602

 ´ 10 – 9

9.109

´ 10 -31

          -1

    1/1836
  • Energy Transfer = Mass ´ Specific heat capacity ´Temperature change

Energy Transferred = M ´ C ´DT

                                           For enthalpy divide by the number of moles.

  • Concentration = moles / volume
  • Working out formula by percentage using RAM,  divide the percentage by the RAM,        E.g. for 22.02% of Carbon(12), 4.59% of hydrogen(1), 73.39% of Bromide(80): we get

22.02 / 12 = ~ 2;   4.59 / 1= ~ 5;   73.39 / 80 = ~ 1     \ C2 H5 Br

 

  • At 20°C; 1 mole of gas will occupy 24 dm cubed, this is the R.T.P.
  • At 0°C; 1 mole of gas will occupy 22.414 dm cubed, this is the S.T.P.
  • Moles = Mass / RAM

 

Radio Active Decay

Basically what happens

Example

µ (alpha ) decay

The release of a helium nucleus

 (2 P and 2N) from the nucleus 

U 238 ® Th 234 + (µ) He 4

    92             90                  2

b (beta) decay

A neutron decomposes to create a

electron and proton, the electron is

then expelled from the nucleus

Po 216 ® At  216 + (b) e 0

      84              84             -1

Gamma Decay

 The nucleus has too much energy,

which makes it unstable, so a pulse

of energy is expelled from the nucleus

Fission

Where a large atom decomposes into

Two smaller atoms and sometimes some

Other neutrons are released

U 235 ® Ba 144 + Kr 90 + 2 N 1

     92              56           36          0

Other Notes in this Category

  1. Forumlae for Nuffield Physics
  2. General Equations and Definitions
  3. Key Chemical Terms and Vocabulary

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