Atomic Structure

Atomic Structure

1. Elements

   • Elements are substances made up of only ONE type of atom
   • Electronic Structure
     • Shells of electrons
       • Shell 1 = 2 electrons Shell 2 = 8 electrons Shell 3 = 8 electrons Shell 4 = 18 electrons

2. Mixture = a substance made of 2 or more simpler substances

3. Molecule = a particle made up of multiple types of atoms

4. Isotopes = atoms with different numbers of electrons

5. Structure of the atom through time

   • Plum Pudding Model = a ball of positive charge with scatterings of negative charge
     • Alpha Scattering Experiment
       • Positive Alpha particles were fired at thin gold foil
         • Most particles passed through easily
           • Most of an atom is empty space
         • A few deflected and a very small number bounced back
           • Positive nucleus
       • Nuclear Model

6. Radius of an Atom is 0.1 nanometre

7. Development of the Periodic Table

   • 1808 John Dalton
     • Organised all known elements in order of atomic weight and did not link to reactivity
   • 1829 Johann Dobereiner
     • Put the elements into groups of 3 similar elements
   • 1866 John Newlands
     • Arranged in groups of 8 and began to notice patterns
   • 1869 Dimitri Mendeleev
     • Similar to Newlands but he left gaps and moved some around
   • Modern Periodic Table
     • NO gaps
     • Noble gases

8. Halogens

   • Fluorine
     • Chlorine
       • Iodine
         • Bromine
         • Astatine
   • Less reactive as you go down the table

9. Alkali Metals

   • Lithium
     • Sodium
       • Potassium
         • Rubidium
           • Caesium
             • Francium
   • More reactive as you go down the table