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					                  Atomic structure

                      Mrs Griffiths
                     Wellington School


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Atomic Structure
          The structure of the atom
    The Ancient Greeks used to believe that
everything was made up of very small particles. I
 did some experiments in 1808 that proved this
       and called these particles ATOMS:



                                                    Dalton



                                               ELECTRON –
                                              negative, mass
                                              nearly nothing
NEUTRON –                      PROTON –
neutral, same                positive, same
   mass as                      mass as
 proton (“1”)                 neutron (“1”)
                 The Atom
     Nucleus                Electron




Shell or Orbit
              The Atom Hydrogen
     Proton                                    Electron




Hydrogen has one proton, one electron and NO neutrons
              The Atom Helium

     Proton                                          Electron




Neutron


Helium has two electrons, two protons and two neutrons
    Mass and atomic number Charge
Particle   Relative Mass Relative
 Proton         1                  1
Neutron         1                  0
Electron        0                  -1


             MASS NUMBER = number of
             protons + number of neutrons

                      SYMBOL


            PROTON NUMBER = number of
                protons (obviously)
              The Atom Helium

     Proton                                          Electron




Neutron


Helium has two electrons, two protons and two neutrons
                     The Atom Lithium
           Protons                      Electrons




Neutrons
                 The Atom Beryllium
           Protons                                        Electrons




Neutrons


   Beryllium has four electrons, four protons and five neutrons.
                     The Atom Boron
           Protons                                            Electrons




Neutrons


   Boron has five electrons, five protons and six neutrons.
                     The Atom Carbon
           Protons                                           Electrons




Neutrons


   Carbon has six electrons, six protons and six neutrons.
                     The Atom Nitrogen
           Protons                                       Electrons




Neutrons


   Nitrogen has seven electrons, seven protons and seven neutrons.
                     The Atom Oxygen
           Protons                                        Electrons




Neutrons


   Oxygen has eight electrons, eight protons and eight neutrons.
                     The Atom Fluorine
           Protons                                         Electrons




Neutrons


   Fluorine has nine electrons, nine protons and ten neutrons.
                     The Atom Neon
           Protons                                         Electrons




Neutrons


   Neon has ten electrons, ten protons and ten neutrons.
                     The Atom Sodium
           Protons                                       Electrons




Neutrons


   Sodium has eleven electrons, eleven protons and twelve neutrons.
How many protons, neutrons and electrons?
            Periodic table
The periodic table arranges all the elements
in groups according to their properties.


Vertical
columns are                                    Mendeleev
called GROUPS




                Horizontal rows are called PERIODS
                   The Periodic Table
   Fact 1: Elements in the same group have the
 same number of electrons in the outer shell (this
        correspond to their group number)

                          H                                                  He
   Li   Be                                             B    C    N   O   F   Ne
        M
   Na                                                  Al   Si   P   S   Cl Ar
        g
                                             C
   K    Ca                      Fe      Ni        Zn                     Br Kr
                                             u
                                             Ag                          I   Xe
                                             A    H
                                        Pt
                                             u    g

E.g. all group 1 metals       These elements have            These elements
have __ electron in           __ electrons in their          have __ electrons
their outer shell             outer shells                   in their outer shell
                The Periodic Table
Fact 2: As you move down through the periods an
         extra electron shell is added:

            E.g. Lithium has 3
                      in
            electronH the                                                 He
            configuration 2,1
  Li   Be                                           B    C    N   O   F   Ne
       M
 Na                                                 Al   Si   P   S   Cl Ar
       g
                 Sodium has 11            C
  K    Ca        electrons in the Ni
                            Fe
                                          u
                                               Zn                     Br Kr
                 configuration 2,8,1
                                          Ag                          I   Xe
                                          A    H
                                     Pt
                                          u    g
            Potassium has 19
            electrons in the
            configuration __,__,__
     Fact 3: Most of the elements are metals:
                The Periodic Table
                         These elements
                         are metals
                   H                                                He

Li    Be                                      B    C    N   O   F   Ne
      M
Na                                            Al   Si   P   S   Cl Ar
      g
                                    C
K     Ca                 Fe    Ni        Zn                     Br Kr
                                    u
                                    Ag                          I   Xe
                                    A    H
                               Pt
                                    u    g
                  This line divides
                                               These elements are
                  metals from non-
                                               non-metals
                  metals
 Fact 4: (Most important) All of the elements in
                The Periodic Table
 the same group have similar PROPERTIES. This
is how I thought of the periodic table in the first
       place. This is called PERIODICITY.
                   H                                                He

  Li   Be                                     B    C    N   O   F   Ne
       M
  Na                                          Al   Si   P   S   Cl Ar
       g
                                     C
  K    Ca                 Fe    Ni       Zn                     Br Kr
                                     u

              E.g. consider the group 1 metals. They all:
                                   Ag                  I            Xe
                                     A   H
              1) Are soft       Pt
                                     u   g

              2) Can be easily cut with a knife
              3) React with water
     Group 1 – The alkali metals

Li
Na
K
Rb
Cs
Fr
            Group 1 – The alkali metals
Some facts…
1) These metals all have ___
electron in their outer shell

2) Reactivity increases as you go _______ the group. This is
because the electrons are further away from the _______
every time a _____ is added, so they are given up more easily.

3) They all react with water to form an alkali (hence their
name) and __________, e.g:
  Potassium + water          potassium hydroxide + hydrogen
   2K(s)   +    2H2O(l)          2KOH(aq)        +       H2(g)

           Words – down, one, shell, hydrogen, nucleus
Group 0 – The Noble gases
                            He
                            Ne
                            Ar
                            Kr
                            Xe
                            Rn
          Group 0 – The Noble gases
Some facts…
1) All of the noble gases have
a full outer shell, so they are
very _____________

2) They all have low melting and boiling points

3) They exist as single atoms rather then diatomic molecules

4) Helium is lighter then air and is used in balloons
   and airships (as well as for talking in a silly voice)

5) Argon is used in light bulbs
   (because it is so unreactive)
   and argon , krypton and neon
   are used in fancy lights
Group 7 – The halogens

                         F
                         Cl
                         Br
                         I
                         At
            Group 7 – The Halogens
Some facts…




                                                         reactivity
                                                                      Decreasing
1) Reactivity DECREASES
as you go down the group

(This is because the electrons are further away from the
nucleus and so any extra electrons aren’t attracted as much).

2) They exist as
diatomic molecules (so
that they both have a          Cl      Cl
full outer shell):


3) Because of this fluorine and chlorine are liquid at room
temperature and bromine is a gas
1) Halogen + metal:
        The halogens – some reactions
                                            +            -

   Na          +      Cl          Na                Cl



               Halogen + metal    ionic salt

2) Halogen + non-metal:


      H    +        Cl                 Cl       H


        Halogen + non-metal      covalent molecule
             How shells fill
• The first electron shell can only hold a
  maximum of two electrons.
• The second electron shell can hold a
  maximum of eight electrons.
• The third electron shell can also hold a
  maximum of eight electrons.
• The fourth electron shell can also hold eight
  electrons.
Consider an atom of Potassium:
                    Electron structure



                                               Nucleus
 Potassium has 19 electrons.
 These are arranged in shells…


The inner shell has __ electrons
The next shell has __ electrons
The next shell has __ electrons                Electron structure
The next shell has the remaining __ electron       = 2,8,8,1
   How the shells fill with electrons
Element   Shell 1    Shell 2    Shell 3    Shell 4


Hydrogen 1 electron 0 electron 0 electron 0 electron
H

Helium    2 electron 0 electron 0 electron 0 electron
He
   How the shells fill with electrons
Element    Shell 1    Shell 2    Shell 3    Shell 4


Lithium    2 electron 1 electron 0 electron 0 electron
Li

Beryllium 2 electron 2 electron 0 electron 0 electron
Be
   How the shells fill with electrons
Element   Shell 1    Shell 2    Shell 3    Shell 4


Boron     2 electron 3 electron 0 electron 0 electron
B

Carbon    2 electron 4 electron 0 electron 0 electron
C
   How the shells fill with electrons
Element    Shell 1    Shell 2    Shell 3    Shell 4


Nitrogen   2 electron 5 electron 0 electron 0 electron
N

Oxygen     2 electron 6 electron 0 electron 0 electron
O
   How the shells fill with electrons
Element    Shell 1    Shell 2    Shell 3    Shell 4


Fluorine   2 electron 7 electron 0 electron 0 electron
F

Neon       2 electron 8 electron 0 electron 0 electron
Ne
    How the shells fill with electrons
Element     Shell 1    Shell 2      Shell 3      Shell 4


Sodium      2 electron 8 electron   1 electron   0 electron
Na

Magnesium 2 electron 8 electron     2 electron   0 electron
Mg
     How the shells fill with electrons
Element     Shell 1    Shell 2      Shell 3      Shell 4


Aluminium 2 electron 8 electron     3 electron   0 electron
Al

Silicon     2 electron 8 electron   4 electron   0 electron
Si
    How the shells fill with electrons
Element     Shell 1    Shell 2      Shell 3      Shell 4


Phosphorus 2 electron 8 electron    5 electron   0 electron
P

Sulphur     2 electron 8 electron   6 electron   0 electron
S
     How the shells fill with electrons
Element    Shell 1    Shell 2      Shell 3      Shell 4


Chlorine   2 electron 8 electron   7 electron   0 electron
Cl

Argon      2 electron 8 electron   8 electron   0 electron
Ar
    How the shells fill with electrons
Element     Shell 1    Shell 2      Shell 3      Shell 4


Potassium   2 electron 8 electron   8 electron   1 electron


Calcium     2 electron 8 electron   8 electron   2 electron
Ca
      The First Twenty Elements
•   Hydrogen 1,0,0,0
•   Helium    2,0,0,0
•   Lithium   2,1,0,0
•   Beryllium 2,2,0,0
•   Boron     2,3,0,0
•   Carbon    2,4,0,0
•   Nitrogen 2,5,0,0
     First 20 Elements continued
•   Oxygen      2,6,0,0
•   Fluorine    2,7,0,0
•   Neon        2,8,0,0
•   Sodium      2,8,1,0
•   Magnesium   2,8,2,0
•   Aluminium    2,8,3,0
•   Silicon     2,8,4,0
     First 20 Elements continued
•   Phosphorus   2,8,5,0
•   Sulphur      2,8,6,0
•   Chlorine     2,8,7,0
•   Argon        2,8,8,0
•   Potassium    2,8,8,1
•   Calcium      2,8,8,2
           The Alkali metals
• Lithium, Sodium and Potassium have one
  electron in their outer shell and this is why
  they are found in group one of the periodic
  table.
           The Nobel gases
• The Nobel gases have full outer shells and
  they are found in group 0 of the periodic
  table. Helium, Neon, Argon, Krypton,
  Xenon and Radon.
             The Halogens
• Fluorine, Chlorine, Bromine and Iodine are
  the Halogens and they all have seven
  electrons in their outer shell. This is why
  they are found in group 7 of the periodic
  table.
             Displacement
• Fluorine can displace Chlorine, Bromine
  and Iodine.




    F         Cl         Br        I
             Displacement
• Chlorine can displace Bromine and Iodine
  but it cannot displace Fluorine




    Cl         Br       I           F
             Displacement
• Bromine can displace Iodine but it cannot
  displace Fluorine or Chlorine




     Br       I           F            Cl
             Displacement
• Iodine cannot displace Iodine Fluorine,
  Chlorine or Bromine




     I            F           Cl       Br
     Fluorine reacts with sodium
     chloride. Which equation is
    correctly shows this reaction?
•     F2 + 2Na  2NaF
•     F + Na  NaF
•     2F + 2Na  2NaF
         Which will displace?
•   2NaF + Cl2  Yes or No
•   2NaBr + Cl2  Yes or No
•   2KI + I2  Yes or No
•   2LiCl + I2  Yes or No
•   2NaBr + I2  Yes or No
•   2NaBr + F2 Yes or No
•   Cl2 + 2NaBr  Yes or No
    Four factors affecting
       Reaction Rate


 Catalysts       Temperature



Concentration   Surface Area
              Catalyst

• A catalyst speeds up or slows
  down a reaction but does not get
  used up by the reaction.
           Temperature

• If we increase the temperature of a
  reaction by 100C the rate will
  double this means the reaction will
  be complete in half the time.
           Concentration

• If we increase the concentration of
  a reactant the number of particles
  increase that in turn increases the
  chance of a collision and initiates a
  chemical reaction.
            Surface area

• The larger the particle size the
  smaller the relative area the slower
  the reaction.
• The smaller the particle size the
  greater the relative surface area and
  the faster the reaction.
                  Group 1
• Lithium, sodium and potassium are all in
  group 1.
• They all have one electron in the outer shell.
• They are all metals.
• They react with group 7 to form metal
  halides.
                 Group 7
• Fluorine ,Chlorine, Bromine and Iodine.
• They all have 7 electrons in their outer
  shell.
• They are all coloured.
• They form metal halides with group 1
  metals.
                  Group 0
•   These are the noble gases.
•   They have complete electron shells.
•   The electron shells are full.
•   They are unreactive.
•   They are inert.
•   They do not react.
•   They include, Helium, Neon, Argon,
    Krypton, Xenon and Radon
                  Halogens
Name     Colour    State    M.P.   B.P.
Fluorine Pale      Gas      -220   -188
         Yellow

Chlorine Green     Gas      -101   -34


Bromine Brown      Liquid   -7     59


Iodine   Slate     Solid    114    184
         grey
                 Reactions
•   Sodium and Chlorine react to form 
•   Sodium Chloride.
•   Iron and Chlorine react to form 
•   Iron Chloride.
•   2Na + Cl2  2NaCl.
•   Fe + Cl2  FeCl2.
        Uses of the Halogens
• Fluorine is put into water supplies to kill
  harmful bacteria and to help keep teeth
  healthy.
• Chlorine is used in swimming pools to
  bacteria in the water.
• Bromine is used in pesticides. Silver
  bromide is used in photography.
• Iodine is an antiseptic on cuts and grazes.

				
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