Atomic structure and the periodic table

Atomic structure and the periodic table

1. Atoms

   • The Nucleus
     • Protons
       • Determines what element it is
       • Positive charge
     • Neutrons
       • Determines what isotope it is
       • neutral charge
   • Electrons
     • Move in shells
       • Determines the period of the element
       • First shell: 2, second: 8, third:8
     • Determines what ion it is
       • More means negative charge
       • Less means positive charge
     • negative charge
   • Neutral and have no charge normally
     • Protons = electrons
   • Protons + neutrons = approximate mass number

2. Elements

   • Contain molecules with one type of atom
   • 118 currently known with more predicted to be possible
   • Represented by symbols

3. Compounds

   • Made of two or more types of atoms
   • Chemically linked through bonds
     • Covalent
     • Ionic
     • Metallic
   • Properties can be totally different from the properties of their elements

4. Mixtures

   • Made of two or more types of atoms or compounds
   • But they are not chemically linked
   • Properties are normally a mix of the properties of their components
   • Can be separated without a chemical reaction

5. Periodic table

   • Groups
     • 0-7 and transition metals
       • Group 1: alkaline metals
         • Very reactve
         • More reactive down the group as the electron is further from the nucleus
         • 1 electron in the outer shell
         • soft metals
         • Low density
       • Group 7: Halogens
         • Less reactive as you go down because the outer shell is further away from the nucleus
         • Very reactive
         • Colored vapors
         • Further down, higher melting points
       • Group 0: noble gasses
         • Inert
         • outer shell always has 8 electrons
         • Further down, higher melting points
   • Periods
     • Currently 7

6. Separating mixtures

   • Chromatography
     • Separating mixtures into their components by allowing one to move and one to stay stationary
     • Paper chromatography separates inks
   • Filtration and crystallisation
   • Distillation and fractional distillation

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