How would you sort these:
A bin of markers?
A deck of cards?
A lot filled with new cars?
HOW WOULD YOU CLASSIFY THESE TYPES OF MATTER?
How Do We Classify Matter in Science?????
Scientists like to classify things.
It wouldn’t help too much to just classify matter based on their color or smell….
One way that scientists classify matter is by its composition (what it is made of).
Ultimately, all matter can be classified as Mixtures or Pure Substances.
Classifying MATTER- we must
start by knowing that …….
The building blocks of all matter
are elements (like on the periodic
table)
Atoms are the smallest unit of
an element that maintains the
properties of that element
For example,
one atom of gold (Au) is
still gold, but if you
broke the atom into
smaller pieces,
it wouldn’t be gold
Pure Substances
An Element is a pure substances made of only one type of atom
For example,
O2 C Ca He
7
Pure Substances
Compounds
A compound is a substance that
is made from the atoms of two
or more elements that are
chemically combined.
Examples: NaCl (salt)
H2O (water)
Classification of Matter
by Composition
All matter can be classified into two
categories: Pure Substances or
Mixtures
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Classification of Mixtures
homogeneous = mixture that has
uniform composition throughout
AKA: Solution
Every piece of a sample has identical
characteristics, though another sample
with the same components may have
different characteristics.
atoms or molecules mixed uniformly
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Page 450
Put the following definitions in your notebook
from the book:
Element
Compound and give example
Heterogeneous Mixture
Colloid and give example
Suspension and give example
Homogeneous Mixture
Then turn over the paper I gave you and
complete
Homogeneous Mixtures
(Solutions)• Solutions
– Appear Uniform
– Mixed particles are dissolved and so small that they don’t reflect light (scattering).
– Nothing settles out over time.
– Nothing filters out.
– Can be in solid, liquid, or gas form!
Classification of Mixtures
heterogeneous = mixture that does not
have uniform composition throughout–
you can see the different parts
contains regions within the sample with
different characteristics
atoms or molecules not mixed uniformly
18
Heterogeneous mixturesYou can see the particles that make
it up.
Sand and pebbles
Oil and water
Cereal
Heterogeneous Mixtures – 2 typesHeterogeneous
• Colloids
– Looks uniform but particles aren’t really dissolved. Particles are still large enough to scatter light. Looks cloudy when light goes through it.
• Suspensions– Don’t look uniform,
filters, settles out over time, and particles scatter light.
Heterogeneous Mixtures – 2 typesHeterogeneous or solution (homogeneous)?
• How can we tell if a mixture is truly homogeneous or heterogeneous?
• SHINE A LIGHT THROUGH IT AND YOU WILL KNOW!
Tyndall EffectThis is the scattering
of light reflecting off
little particles.
Solution: cannot see
beam of light
Heterogeneous: you
can see beam of light
(reflecting off litte
particles)
Density
Density –
More dense objects will sink when
compared to less dense objects.
What do you think has the highest
density?
WATER, OIL, MOLASSES?
Density
Density – How much
matter is contained in
a certain volume
D=mass/volume
What is more dense,
a cup of unpopped
popcorn kernels or a
cup of popped
popcorn?
Bellringer 11-12-13
1. A lot of medicines are kept in dark
brown bottles (not clear) What kind of
change (do you think) is being
prevented by keeping the sunlight out?
Physical or Chemical
2. If you let saltwater evaporate, the salt is
left behind. This is a method of making
drinking water from sea-water called
desalination. Is this a physical or
chemical change?