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All matter can be grouped
into two categories: pure substances and mixtures.
Pure Substances can be:
·
Elements—all
the atoms are the same
o
Ex. Copper, Oxygen, Helium, Calcium, etc.
o
Basically,
anything on the periodic table
·
Compounds—when
elements combine chemically in certain ratios
o
Ex. H2O
(2 hydrogens and one oxygen)
o
The compound does
not have the same properties as the original elements
o
Na (metal) + Cl (toxic gas) à NaCl (salt!)
Mixtures are when 2 or more substances are combined. They can be:
· Homogeneous
Mixtures—when the composition of
the mixture is the same everywhere
o
Solutions
are homogeneous mixtures of liquids
o
Ex. Kool-Aid,
salt water (anything evenly mixed)
· Heterogeneous
Mixtures—when the composition of
the mixture is different in different parts
o
Ex. Mixed
nuts—more peanuts at the bottom
o
Ex. Orange
Juice—pulp settles to the bottom
o
Suspensions—mixtures
that settle when left standing (like muddy water or orange juice)
o
Colloids—small
particles do not settle out (ex. milk)
