Pure Substances: Matter that always has the same composition
ex. table salt, sugar, sulfur,
fixed, uniform composition: every sample of a given substance has the same properties
2 categories
-elements
ex. H, O, Si, C
-compounds
ex. NaCl, KBr
Elements: - a substance that can not be broken down into simpler substances
-119 elements
-88 are found naturally,about 90%
-not equally common
-others are made in laboratories
Elements Cont:
-majority of the elements are not found in abundance
-some are exceedingly rare
-only a dozen or so make up everyday things
primarily: carbon, hydrogen, oxygen, nitrogen
Compounds:
a substance made of atoms of more than one element bound together
unique and different from the elements it contains
ex. Water: (H2O) liquid, clear, non toxic
ClassifyingMatterCont.
Mixtures- combination of more than one pure substance
ex. salsa, air, salad, pepper.
Two types of mixtures
heterogeneous and homogenous
Heterogeneous
-not uniform in composition
-different components can be seen as individual substances
ex: Oj: juice & water, pulp
Suspension(Heterogeneous)
-mixtures that separates into layers over time
-suspended particles settle out of solution or are trapped by filter
-larger particles can scatter light: will be cloudy
ex. O.J., sand/water, muddy water
Homogenous
-substances are so evenly distributed that it is difficult to distinguish one substance from another
-appears to contain only one substance
ex. stainless steel: iron, nickel, chromium
Solutions(Homogenous)
-mixtures that forms when substances dissolve and form a homogenous solution
-particles are too small to settle, scatter light, or be trapped
ex. salt water, windshield wiper fluid
Colloids(Heterogeneous)
-mixtures that contain some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension.
Colloids (Heterogeneous) do not separate into layers