Ok, what is it with this whole Chemistry thing?

Well I suppose the starting point is this: Chemists separate the vast world of matter (everything that takes up space and has mass into two giant categories: Pure Substances and Mixtures.

Pure substances                                                  (Polly Purebred)

    Now pure doesn't mean moral, or nutritious or good (like our Polly Purebred above). To a chemist pure means only
    one thing. Made from only 1 kind of molecule.

Compounds

     Take for instance sugar yum!!! : )    

We can see that the sugar crystals are pure. Only the very best for you. But by reacting sugar with
     other chemicals we know that sugar is made of molecules (different atoms bonded together to make a new substance).

    Every molecule of sugar has carbon and oxygen and hydrogen in very specific ratios. If fact the simplest  sugar has a
     chemical formula of  C₆H₁₂O₆ . All of these atoms are bonded together and act as a unit. This is the smallest unit that
     has the properties of sugar. A pure substance made of molecules with more than one type of atom is called a compound.

    Elements

    The second class of pure substances are elements. Many of these don't really have molecules (just big piles of the same
     type of atom). Those that have molecules are made of just one type of atom. That is what makes them an element. They
     cannot be broken down to anything simpler by normal chemistry. What could be simpler than having just one type of part?

    How about some stinky sulfur for example: Its an S₈ molecule, but every atom is S. So its
     an element. Elementary right??? : )

Or N₂ molecules which is 80% of our air. Again, another element, 'cause even though its a
     molecule it only has one type of atom.

    Many metals, like zinc, shown below are just piles of atoms packed as closely as possible. They are of no particular size and
    aren't really considered molecules. Zinc crystal

Mixtures

    Mixtures aren't pure substances. They have at least 2 kinds of molecules. Mixtures come in two varieties as well.

    Inhomogeneous mixture

    These mixtures have visible parts or layers. Keep in mind this depends on the scale of observation. To you and me, a drop
     of blood is all the same. To a doctor it has red blood cells, and several types of white cells, plasma and other stuff like
     maybe germs. Since it can be shown to have parts inhomogeneous, but if you're looking at a bucket of it. Homogeneous. 
    It depends on the scale of observation

    More obvious inhomogeneous mixtures would be like chocolate chip cookies, or trail mix. Ugh, leave out the raisins!! : o

    Inhomogeneous, pick out your favorite pieces. Oil and water inhomogeneous mix.

    Homogeneous mixture

Drops of sea water all have the same salinity. So they might be an example of a homogeneous mixture.
    Every drop would have same ratio of Na ions, Cl ions and H₂O molecules. When every part is the same its homogeneous.