Combinations of Atoms by INB27a


									Combinations of
   September 3, 2009

• When the atoms of more than one element
  combine, they form a compound.
     Water (H20)= 2 Hydrogen+ 1 Oxygen
      Salt (NaCl)= 1 Sodium+ 1 Chloride
              Sugar (C12H22O11)=
     12 Carbon+22 Hydrogen+ 11 Oxygen
    How do compounds form?
When atoms chemically bond together they form a
 compound by sharing or exchanging electrons. We
   are going to look at 4 types of chemical bonds.
             Covalent Bonds
• This type of bond is when atoms SHARE an
  electron. A group of atoms connected by
  covalent bonds are called molecules.

Example: Water! The 1 oxygen atom shares its
         electrons with the 2 hydrogen atoms.
                Ionic Bonds
• When atoms are electrically charged they are
  called ions. If the atom have more electrons
  than protons then the atom is negatively
  charged. If the atom has more protons than
  electrons then the atom is positively charged.
  Sodium ion (+)               Chloride ion (-)
        Ionic Bonds Continued
• Ions of opposite charges are attracted to each
  other. (similar to magnets)
 So the Sodium (Na) Ion (+) attracts the Chloride
                      (Cl) Ion(-)
  and they form an ionic bond which no longer
                     has a charge.
           NaCl is made, which is SALT!
             Metallic Bonds
• These bonds are found in metals such as
  copper, gold, aluminum, and silver. These
  bonds allow the electrons to move freely
  which makes them easily pass an electric
  current through them.
        Steel: Bonding iron and carbon
        Brass: Bonding copper and zinc
            Hydrogen bonds
• These bonds form without any interaction of
  electrons. These bonds are very important to
  everyday life: showering, boiling vegetables,
  making tea, and riding on a boat.
  Examples: penny and dropper
             paper clip and petri dish
• Combining 2 or more substances that are not
  chemically combined. Think of a salad!
       Heterogeneous mixtures
• These mixtures are not mixed evenly and each
  part keeps its own properties.

   Salads are great examples of heterogeneous
        Homogenous mixtures
• Mixtures that are evenly mixed. You can’t see
  the parts anymore. Another name for this
  type of mixture is a solution.
 Ocean water (salt and water)is a great example!
 Separating Mixtures and Compounds
• You can physically separate mixtures. Try picking
  out the carrots, lettuce, and tomatoes out of a
  salad. When you let ocean water evaporate in a
  cup you have salt left. (EASY)
• Compounds must be separated by chemical
Example: C12H22O11 (sugar)+ H2SO4 (sulfuric acid)
  The sulfuric acid removes water from the sugar,
     which releases heat, steam, and sulfur oxide
   fumes. All that is left of the compound is carbon.

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