1. Classification of Matter

2. Every sample of matter can be classified as a:
Pure Substance
Mixture
Element
Molecule
Diatomic molecule
Compound
Homogeneous
Solution
Heterogeneous
Colloid
Suspension

3. Pure Substances
Pure Substances cannot be broken down into any other substances by physical means
Gold - element
Manganese Dioxide - compound

4. Pure Substance Element composed of identical atoms
EX: copper wire, aluminum foil
Courtesy Christy Johannesson

5. Molecules Groups of two or more atoms bound by chemical bonds
Can be two of the same element

6. Pure Substances
Compounds are either molecules or salts – need more on salts
Courtesy Christy Johannesson

7. Sodium Chloride – NaCl (Table Salt)
Sodium (Na) - Metal
Chlorine (Cl) - gas
Sodium Chloride NaCl
Fixed ratio: 1 Na for every 1 Cl
Sodium in water video

8. Pure Substances - FYI Law of Definite Composition
A given compound always contains the same, fixed ratio of elements.
Two different compounds, each has a definite composition
Courtesy Christy Johannesson

9. Diatomic Elements, 1 and 7 H2 N2 O2 F2
Cl2
Br2 I2

10. Diatomic molecules are molecules composed only of two atoms, of the same elements. The prefix di- means two in Greek. Common diatomic molecules are hydrogen (H2), nitrogen (N2), oxygen (O2), Fluorine (F), Chlorine (Cl), Bromine (Br), and Iodine (I).

11. Chemical Formulas
Shows the compound and the ratio of atoms

12. Mixtures
Variable combination of two or more pure substances. Each keep individual properties
Heterogeneous – Can see different parts (different)
Homogeneous- Evenly Mixed cannot see different parts. (Same)
Courtesy Christy Johannesson

13. Tyndall Effect The scattering of light by particles in a mixture

14. Mixtures Solution homogeneous very small particles no Tyndall effect
particles don’t settle
Examples:
rubbing alcohol (ethyl alcohol and water)
Air (nitrogen and oxygen)

15. Mixtures Colloid heterogeneous medium-sized particles Tyndall effect
particles don’t settle
Particles scatter light
EX:
Milk
Clouds
Smoke
mayo
Courtesy Christy Johannesson

16. Mixtures Suspension heterogeneous large particles Tyndall effect
particles settle
EX:
fresh-squeezed lemonade
Sand in water
Courtesy Christy Johannesson

17. MATTER yes no MIXTURE PURE SUBSTANCE yes no yes no Homogeneous Mixture
Can it be physically separated?
MIXTURE
PURE SUBSTANCE
yes
Is the composition uniform? no
yes
Can it be chemically decomposed? no
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element
Colloids
Suspensions
Courtesy Christy Johannesson

18. Elements, Compounds, and Mixtures
Consider Concentration Here!
oxygen atoms
hydrogen
atoms
hydrogen
atoms
“Elements, Compounds, and Mixtures”
Description: This slide shows the molecular composition of an element, a compound, and two mixtures.
Basic Concepts
All samples of a substance have the same molecular composition and intensive properties and are homogeneous.
Elements and compounds are substances; mixtures are not.
The elements making up a compound combine in fixed ratios.
Mixtures can be separated by physical methods.
Mixtures that have a uniform composition throughout are homogeneous; those that have parts with different compositions are heterogeneous.
Teaching Suggestions
Use this transparency to help students visualize the molecular composition of elements, compounds, and mixtures and to review the definitions of these terms. Make sure students understand the difference between the terms matter and substance. Remind students that elements and compounds are always homogeneous, while mixtures can be either homogeneous or heterogeneous.
Questions:
Which of the bottles pictured above contain(s) matter? Which contain(s) a single substance? Explain your answers.
How many elements are present in each molecule of water shown in bottle (b)? What is the relative number of atoms of each element in a water molecule?
As you know, ice is frozen water. In other words, ice and water are the same substance, in different phases. What would you expect the ratio of hydrogen atoms to oxygen atoms to be in a molecule of ice? Explain your reasoning.
Bottle (c) and bottle (d) both contain mixtures. How are these mixtures similar? How are they different?
Suppose you find an unlabeled bottle containing a clear liquid. Can you tell by looking at it whether the material is a compound or a mixture? Explain your answer.
How can you prove that a sample of sea water is a mixture?
Classify the following items as elements, compounds or mixtures; rice pudding, copper, carbon dioxide, air, milk, magnesium chloride, granite, mercury, and maple syrup.
A chocolate-chip cookie with more chips in one part of the cookie than another can be used to demonstrate a heterogeneous mixture. Name two other materials that can be classified as heterogeneous mixtures. Explain your reasoning.
(a)
an element
(hydrogen)
(b)
a compound
(water)
(c)
a mixture
(hydrogen
and oxygen)
(d)
a mixture
(hydrogen
and oxygen)
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68

19. Both elements and compounds have a
definite makeup and definite properties.
Mixtures
two or more
substances
that are
physically
mixed
Elements
only one kind
of atom; atoms
are bonded if
the element
is diatomic or
polyatomic
Compounds
two or
more kinds
of atoms
that are chemically
bonded
substance
with
definite
makeup
and
properties

20. Classification of Matter
hetero-
geneous
mixture no
uniform
properties? no
solution
fixed
composition? no
element
chemically
decomposable?
yes
compound

21. Compounds vs. Mixtures
Compounds have properties that are uniquely different from the elements from which they are made.
A formula can always be written for a compound
e.g. NaCl  Na + Cl2
Mixtures retain their individual properties.
e.g. Salt water is salty and wet

22. Classification of Matter
(gas. Liquid,
solid, plasma)
Separated by
PURE
SUBSTANCES
MIXTURES
physical means into
Separated by
COMPOUNDS
ELEMENTS
HOMOGENEOUS
MIXTURES
HETEROGENEOUS
MIXTURE
chemical
means into
Kotz & Treichel, Chemistry & Chemical Reactivity, 3rd Edition , 1996, page 31

23. Classification of Matter
                                                                                                                                                      
Matter
Physically
separable
Substance
Definite composition
(homogeneous)
Mixture of
Substances
Variable composition
Basis for separation: different components, different properties.
Strategy: devise a process that discriminates between components with different properties.
high density / low density reactive / inert volatile / nonvolatile
soluble / insoluble polar / nonpolar magnetic . nonmagnetic
Chemically
separable
Element
(Examples: iron, sulfur,
carbon, hydrogen,
oxygen, silver)
Compound
(Examples: water.
iron (II) sulfide, methane,
Aluminum silicate)
Homogeneous mixture
Uniform throughout,
also called a solution
(Examples: air, tap water,
gold alloy)
Heterogeneous mixture
Nonuniform
distinct phases
(Examples: soup,
concrete, granite)

24. Mixture vs. Compound Different Alike Different Topic Topic Mixture
Involve
substances
Variable
Composition
Fixed
Composition
Topic
Topic
No bonds
between
components
Contain
two or more
elements
Bonds
between
components
Mixture
Compound
Compounds have different properties than the elements they are made from. In a mixture, the mixture retains the properties of the materials it is made from.
A chemical formula can always be written for a compound.
Can be
separated by
physical means
Can be
separated
into
elements
Can ONLY be
separated by
chemical means

25. Top Ten Elements in the Universe
Percent
Element (by atoms)
Hydrogen 73.9
Helium 24.0
Oxygen
Carbon
Neon
Iron
Nitrogen
Silicon
Magnesium
Sulfur
A typical spiral galaxy
(Milky Way is a spiral galaxy)
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 26

26. The Composition of Air Air Nitrogen Helium Oxygen Neon Water vapor
Carbon
dioxide
Argon
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 34

27. Chart Examining Some Components of Air
Nitrogen consists of molecules consisting of
two atoms of nitrogen:
Oxygen consists of molecules consisting of
two atoms of oxygen:
Water consists of molecules consisting of two
hydrogen atoms and one oxygen atom:
Argon consists of individual argon atoms:
Carbon dioxide consists of molecules consisting
of two oxygen atoms and one carbon atom:
Neon consists of individual neon atoms:
Helium consists of individual helium atoms: N2 O2
H2O Ar
CO2 Ne He
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 35

28. Matter Flowchart Examples: graphite pepper element sugar (sucrose)
paint
soda
element
hetero. mixture
compound
hetero. mixture
Graphite image: geology.about.com/.../bl/images/blgraphite.htm
solution
homo. mixture
Courtesy Christy Johannesson

29. Mixtures Examples: colloid suspension colloid solution suspension
mayonnaise
muddy water
fog
saltwater
Italian salad dressing
colloid
suspension
colloid
solution
suspension
Courtesy Christy Johannesson

30. Reviewing Concepts Classifying Matter
Why does every sample of a given substance have the same properties?
Explain why the composition of an element is fixed.
Describe the composition of a compound.
Why can the properties of a mixture vary?
On what basis can mixtures be classified as solutions, suspensions, or colloids?
Prentice Hall Physical Science Concepts in Action (Wysession, Frank, Yancopoulos) 2004 pg 44
Every sample of a given substance has the same properties because a substance has a fixed, uniform composition.
An element has a fixed composition because it contains only one type of atom.
A compound always contains two or more elements joined in a fixed proportion.
The properties of a mixture can vary because the composition of a mixture is not fixed.
Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.

31. Separating a Mixture

32. Separating a Mixture
Chromatography - To separate different colored dyes. The dyes travel up the chromatography paper at different distances before they cannot remain in solution. The more soluble dyes move further up than the less soluble ones, hence separating from each other.

33. Separating a Mixture
Distillation - to separate and collect a liquid from a solution of a soluble solid. The solution is heated in a flask until the liquid boils. The vapor produced passes into the condenser where it is cooled and condenses to a liquid. The pure liquid (distillate) is collected in a beaker.

34. Separating a Mixture Evaporation –
This method is suitable to separate a soluble solid from a liquid. If the solution is heated, the liquid evaporates leaving the solid behind.

35. Separating a Mixture
Fractional Distillation - This is a special type of distillation used to separate a mixture of liquids. Different liquids boil at different temperatures. When heated, they boil off and condense at different times. The apparatus features a fractionating column, which ensures that only the liquid boils at its boiling point will pass into the condenser.

36. Separating a Mixture Filtration –
To separate an insoluble solid from a liquid. The solid remains in the filter paper and the liquid goes through the paper into the beaker.