Chapter 2 Powerpoint

1. Chapter 2
Amy Goltermann

2. Chapter 2.1
Matter
Pure
Mixture
Substance
Hetero-
Element Compound Homogeneous
geneous

3. Chapter 2.1
What is a pure substance?
A pure substance…
• Made up of either compounds and/or elements
• Has a unique set of properties
Pure
• Can only be separated chemically Substance
• Can only be combined in a fixed uniform
ratio
Some examples of pure substances are…
• Salt
• Sugar

4. Chapter 2.1
What is an element?
An element…
Is a substance that cannot be broken down
Has a fixed composition because it only has one type
of atom
Examples of elements:
Oxygen
Hydrogen Element
Unununium

5. Chapter 2.1 Compound
What is a compound?
A compound…
Is a substance made from two or more simpler substances
that can be separated
Is always in a fixed proportion/ ratio
*Note- a compound will always have two more elements
that make up the composition (some of the elements
combined are compounds)
Some examples of compounds are…
Silicon dioxide
Water

6. Chapter 2.1
What is a mixture?
A mixture…
Mixture
Can be combined in any ratio
Does not have a unique set of properties
This grain of
Can be separated physically sand is different
Some examples are…
Salsa
Pool water
Sand Than this grain of
sand

7. Chapter 2.1
What is a heterogeneous mixture?
In a heterogeneous mixture the
parts are noticeably different and
and each part can be taken
separated easily.
Salsa is a good example of a
heterogeneous mixture because
you can add as many jalapeño
peppers but take out some of the
onions (no fixed ratio).
It is also a good example because it
is easy to identify different
ingredients and separate them.

8. Chapter 2.1
What is a homogeneous mixture?
In a homogeneous mixture the parts are
evenly distributed so it is difficult to tell the
difference between two substances of the
same origin.
Sometimes in a homogeneous mixture, one
of the parts will dissolve (like when you put
sugar in water). See solutions!
Pool water is a good example of a
homogeneous mixture because you can
take a sample from both the deep end and
shallow end of the pool. The water will look
the same but there will be different
chemicals in each one.

9. Chapter 2.1
Solutions Suspensions and Colloids
Liquid solutions: when a substance dissolves and becomes a homogeneous
mixture
Does not separate into layers
Cannot be separated through a filter
Light can pass through without scattering
Suspensions:
Separates into layers (over time)
Can use a filter
Light is scatters, it is cloudy and you can’t see through it
Colloid:
Contains medium sized particles
Does not separate into layers
Particles spread out evenly

10. Chapter 2.2
Physical
Properties!

11. Chapter 2.2
What are the physical properties?
There are many different physical properties to test for in a
substance but the main ones are:
Viscosity
Conductivity
Malleability
Hardness
Melting point
Boiling Point
Density

12. Chapter 2.2
Viscosity and Conductivity
Viscosity is how resistant a substance to
flowing or moving (this property is tested
mainly with liquids)
Honey is a good example of a liquid with
a high viscosity
Conductivity is how well a substance
conducts heat. Often, if a substance has a
high conductivity, it will be a good
conductor of heat as well
Most metals are good conductors of heat

13. Chapter 2.2
Malleability and Hardness
Malleability and hardness are confusing and
often confused with each other. Here are some
definitions to help keep these two straight.
Malleability is the ability to be hammered
without shattering. Sometimes this
property comes into play when shaping an
object like a coin.
Most metals are malleable and some
substances like glass and ice are brittle
Hardness can be found be testing an object’s
ability to be scratched. The object that scratches
is harder that the scratched object (that’s a lot
of objects and scratches)
The hardest substance known is diamond

14. Chapter 2.2
Melting and Boiling Point
Every substance has a melting and boiling
point (not when in gas form though). The
melting point for water is somewhere
above 0˚c and the boiling point is 100˚c.
Each substance has a different melting
and boiling point.
To test whether a substance is pure or an
alloy, you could use melting point. Melt
the substance. If it all melts at the same
temperature, it is a pure substance. If
some of it melts but there are still some
solid chunks, it is an alloy.

15. Chapter 2.2
Density
The formula for density is:
One can use density to test multiple object to see if
they are the same substance or to compare multiple
unknown substances
Some of the uses of the physical properties are to
identify or choose materials and to separate or
compare substances

16. Separation
Techniques!

17. Separation Techniques
Distillation
A process that separates the substances in a solution
based of boiling points.
Plateau Plateau
100
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18. Separation Techniques
Distillation
When there are multiple plateaus in your data
(testing an unknown substance), you know that
there are multiple boiling points in the substance
inferring that the substance is in face a mixture
Collecting these substances in the mixture separately
is a piece of cake if you can identify the plateaus (use
the same set up for the experiment as in the
“Unknown Substance” lab but collect the liquid in
test tube after each plateau)
The buffer is the liquid in between plateaus. It is a
mixture. It is what is left from the first substance to
boil and the substance that hasn’t boiled yet.

19. Separation Techniques
Filtration
A process that separates
materials based on the size of
their particles and/or solubility
The technique of filtration is Funnel
the same for any experiment
but filters come in all shapes
and sizes.
Filter
A common household item Paper
that is also a filter is the
colander
Filtrate

20. Separation Techniques
Evaporation
A process used to isolate a solid dissolved in a liquid
DISCLAIMER: when you use this technique, you are
only going to be able to isolate the solid because the
liquid will evaporate into air
Example:
NaCl (salt) and water
Salt dissolves in water but you can use evaporation to be
able to obtain the salt after it has dissolve.

21. Chapter 2.3
Chemical
Properties!

22. Chapter 2.3
Chemical Properties
When, what, where, why?
Chemical properties can be observed when the
substance in a sample of matter are changing into
different substances.

23. Chapter 2.3
Flammability
Flammability: a material’s ability to burn in the presence
of oxygen
Not always desirable
Laws regulating fabric’s flammability (needs to be
flame resistant)

24. Chapter 2.3
Reactivity
Reactivity: how readily a substance
combines chemically with other substances.
Oxygen- high reactivity
Iron- high reactivity
Potassium- high reactivity
Nitrogen- low reactivity

25. Chapter 2.3
Evidence of Reactivity
Change in color- relation to change in time
Production of gas
Formation of precipitate
A change in temperature

26. Review Questions
What is the difference between a pure substance and
a mixture?

27. Review Questions
Explain the difference between a solution, a
suspension and a colloid?

28. Review Questions
Please fill in the
chart:

29. Review
Physical Properties Chemical Properties
Please name three Please name three
differences differences.

30. Review
Physical Properties Chemical Properties
Please name all properties Please name all properties

31. I hope you learned a lot about
types of matter and physical
properties during the
presentation! Thanks for
watching!