Unit 4
particle drawings
elements: the same throughout
and
and
all represent elements
compounds: different types of elements bonded together
and
and
all represent compounds
Objective 1. Distinguish between a pure substance and a mixture by
 properties
 separation techniques
 composition (macro- and microscopically)
Mixture =
composition
more than one substance (different elements and/or compounds put together
parts of a mixture are not chemically combined
properties are mixed - different boiling points, magnetism, etc.
can be sehttps://www.youtube.com/watch?v=qpDljy0U8zgparated by physical
means - magnet, filtration, distillation
Filtration
Distillation
particle drawings of mixtures
and
and
Pure substance =
composition one substance only: one type of element, or one type of compound.
if a compound, the elements that make up the compound are chemically combined
properties are the same for all of a pure substance = same boiling point, etc.
can be separated chemically. We observed hydrolysis in the lab (separating water
into its elements, hydrogen and oxygen) using the electricity in the Hoffman apparatus,
below)
Particle drawings
Objective 2. Describe how to use characteristic properties to separate the components of a
mixture:
 identify the separation technique (name, equipment)
 identify the property used in the separation
Objective 3. Cite evidence for the presence of “compounded” matter particles;
Describe the differences between elements and compounds
Compounds can be split into elements (like we split water into hydrogen and oxygen, using
the Hoffman apparatus).
Also, elements can be combined to form new substances, like in the video where sulfur and
iron reacted to form iron sulfate. And see below…
Objective 4. State Avogadro’s Hypothesis (AH) and the evidence that led to this hypothesis.
Use AH along with combining volumes of gases to deduce the composition of some compounds
At equal temperature and pressure, equal volumes of different gases have equal numbers of
particles, even if the gas molecules are of different sizes.
See the Chem lab video to review this…
https://www.youtube.com/watch?v=qpDljy0U8zg
Objective