Properties of Matter: Mini-lectures 1 and 2
Matter (Stuff of
the Universe)
Homogenous
(Solution)
Pure
Substances
Compound
Element
Heterogenous
Mixtures
Matter:
material which has mass and takes
up space (volume)
Pure Substances:
matter with the same fixed composition
and properties.
Elements:
cannot be broken down into simpler
substances (every element on the periodic table).
Atom:
the smallest particle that still has properties of an
element.
Compound:
a bonded combination of two or more elements
that cannot be separated by physically separated.
Molecule: the smallest discrete particle that can still
represent a compound (some elements are found in nature
as molecules).
Formula Unit:
the simplest ratio of ions in an ionic
compound.
State of Matter:
solid, liquid or gas
Mixture:
Phase:
A physical combination of two or more substances.
Part of a mixture with the same properties.
Heterogeneous Mixture:
A combination of two or more
substances that is not the same throughout (i.e. oil and water).
Homogeneous Mixture (Solution):
A
combination of two or more substances that are uniformly
distributed.
Aqueous:
A substance dissolved in water.
Distillation
Chromatography
Decanting
Techniques for separating mixtures using the
physical properties of the substances
Heterogeneous Mixture
Solution
Properties of Matter
Physical Properties--a characteristic of matter that exists without
changing the matter
examples: melting point, freezing point, physical state
(usually at room temperature), volatility, density, volume
mass, solubility
Chemical Properties--a characteristic of matter that only
exists when changing the matter to another substance
examples: flammability, tendency to corrode, color
change, heat or light emission
Changes in Matter
Physical Change--a change in the physical
characteristics of matter which does not result in making
a substance with new properties.
Chemical Change--a change in which substances
are converted into entirely different substances
with different physical and chemical properties
Types of Chemical Changes
Decomposition
reaction which includes the breakdown of more complicated
compounds into (new) less complicated compounds or elements
(i.e. composting pile, decaying organisms, Cu Lab Step 3)
Precipitation
reaction where a new solid is formed from a mixture of aqueous
solutions (i.e. sugar forms in cooling iced tea, Cu Lab Step 2)
Oxidation-Reduction
reactions where electrons are transferred between two substances
resulting in new substances
(i.e. rusting or any type of corrosion, Cu Lab Steps 1 and 5)
Chemical Reaction—any change, physical or chemical in
nature; involves reactants and different products, either in
state or composition, written as a chemical equation
2H2(g) + O2(g)
H2O(g)
Reactants
2H2O(l)
H2O(l)
Products
All Chemical Reactions follow the Law of Conservation of Mass:
the mass of the reactants will equal the mass of the products in
any non-nuclear reaction.
However, in actuality, some mass will be lost in the experimental
process which is performed. The amount you collect of product, is
typically less than that of reactant. SO, a special yield based on
the Law of Conservation of Mass is performed.
Theoretical Yield: The mass of product that should be
produced in a reaction. This is based on the mass of the
reactants, or on a stoichiometric calculation.
Actual Yield: The mass of product that is formed when the
reaction is carried out. This is what is measured in the lab.
Percent Yield: The ratio of the actual process results to the
anticipated process results. The percent yield should NEVER
be greater than 100%, but it often is calculated as such
because of experimental error.
= Percent Yield
Attachments