section 1 composition of matter
TRANSCRIPT
Ch 18 Section 1
Composition of Matter
Pure Substance Pure substance is a type of matter made with a
fixed composition.
Substance can either be an element or a compound.
Ex: helium, aluminum, water, and salt.
Element All substances are built from atoms.
If all the atoms are the same then the substance is an element.
90 elements are found on earth
More than 20 elements have been made in a laboratory.
Compounds A pure substance in which two or more elements
are combined in a fixed proportion.
Ex: salt (NaCl), water (H2O)
Molecules Particles consisting of two or more atoms that are
bonded together.
Mixture Heterogeneous Mixture- a mixture in which
materials can be distinguished easily. Ex: pizza
Homogeneous Mixture- a mixture in which the substances are mixed evenly throughout.
Ex: Unopened soda
Solution A homogeneous mixture with particles so small
that they will never settle to the bottom.
Colloids A type of mixture with particles that are larger than
those in solutions but not heavy enough to settle out.
Tyndall effect
Suspension A heterogeneous mixture containing a liquid in
which visible particles settle. Ex: Pond water