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
Take for instance sugar yum!!! : )
can see that the sugar crystals are pure. Only the very best for you. But by
reacting sugar with
Every molecule of sugar has carbon and oxygen
and hydrogen in very specific ratios. If fact the simplest sugar has a
The second class of pure substances are
elements. Many of these don't really have molecules (just big piles of the same
How about some stinky sulfur for example: Its
an S8 molecule, but every atom is S. So its
Or N2 molecules
which is 80% of our air. Again, another element, 'cause even though its a
Many metals, like zinc, shown below are just
piles of atoms packed as closely as possible. They are of no particular size and
Mixtures aren't pure substances. They have at least 2 kinds of molecules. Mixtures come in two varieties as well.
These mixtures have visible parts or layers.
Keep in mind this depends on the scale of observation. To you and me, a drop
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.
Drops of sea water all have
the same salinity. So they might be an example of a homogeneous mixture.
The air we breathe is also a homogeneous mixture. Each breath is 80% nitrogen and 20% oxygen.