1. Classification of Matter

2. Mixtures, elements, compounds
Scientists like to classify things.
One way that scientists classify matter is by its composition.
Ultimately, all matter can be classified as mixtures, elements and compounds.

3. Why isn’t it a good idea to classify matter by its phases?
Because one kind of substance can exist in more than one phase – such as H20. And matter changes phases rather easily.

4. Why isn’t matter classified according to its physical characteristics, such as color?
Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together.

5. Composition of Matter Flowchart
yes no
Can it be physically separated?
MIXTURE
PURE SUBSTANCE
Is the composition uniform? no
yes
Can it be chemically decomposed? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element

6. Classifying Matter by Composition
Mixtures- are a blend of two or more kinds of matter, each of which retains its own identity and properties.
A mixture is mixed together physically.
Variable composition, often expressed by a percent composition by mass or volume (Ex. 5% salt and 95% water

7. Classifying Matter by Composition
Homogeneous – matter with a uniform composition. They are also called solutions. Ex. Salt water and Kool –aid
Heterogeneous - matter without a uniform composition

8. Homogeneous Mixtures A mixture that appears to be the same throughout.
It is “well mixed.”
The particles that make up the mixture are very small and not easily recognizable.

9. Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous
mixtures. They are also colloids.

10. Colloids
In a colloid the particles are mixed together but not dissolved.
The particles are relatively large and are kept permanently suspended.

11. Colloids A colloid will not separate upon standing.
The particles are constantly colliding, and this allows a colloid to scatter light – thus colloids often seem cloudy.

14. Solutions
A solution is a type of homogeneous mixture formed when one substance dissolves in another.
It is the best mixed of all mixtures.
A solution always has a substance that is dissolved and a substance that does the dissolving.
The substance that is dissolved is the solute and the substance that does the dissolving is the solvent.

15. Ocean water is a solution

16. Water as a solvent Many liquid solutions contain water as the solvent.
Ocean water is basically a water solution that contains many salts.
Body fluids are also water solutions.

17. Metals dissolved in metals are called alloys.
Types of solutions
Solute
Solvent
Example
Gas
Air (oxygen in nitrogen)
Liquid
Soda water (carbon dioxide in water)
Solid
Ocean water (salt in water)
Solid
Gold jewelry (copper in gold)
Metals dissolved in metals are called alloys.

18. Air is a solution of oxygen and other gases dissolved in nitrogen

19. Alloys Stainless steel is a mixture of iron and chromium.
Brass is an alloy of copper
and zinc.

20. Classifying Matter by Composition
A heterogeneous mixture is not the same throughout (not uniform).
Considered the “least mixed.”
Does not appear to be the same throughout.
Particles are large enough to be seen and to be separated from the mixture.

21. Examples of heterogeneous mixtures
Sand and pebbles, gravel, soil, rocks
Oil and water, salad,
M & M’s, Chocolate cookies.

22. Granite is a heterogeneous mixture.

23. Mixtures are separated by their physical properties.
Separating Mixtures
Mixtures are separated by their physical properties.
Primary methods of separating
mixtures are:
filtration
distillation
centrifuge
chromatography

24. Separating Mixtures
Filtration is a method used to separate the components of mixtures that contain an insoluble solid and a liquid. Example: sand and water

25. Separating Mixtures
Distillation is a method of separating substances in a mixture by evaporation of a liquid and subsequent condensation of its vapor. Example: desalination of salt water

26. Distillation Apparatus

27. Separating Mixtures Centrifuge
Used to separate solid-liquid mixtures such as those in blood. The centrifuge spins rapidly and causes the solid to settle to the bottom.
Ex. Separating blood

28. Separating Mixtures
Chromatography is a method of separating mixtures that uses a stationary phase and a mobile phase. Paper chromatography can be used to separate pigments because they move at different rates on the paper.

29. Composition of Matter Flowchart
yes no
Can it be physically separated?
MIXTURE
PURE SUBSTANCE
Is the composition uniform? no
yes
Can it be chemically decomposed? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element

30. Classifying Matter by Composition
Pure Substances- A pure type of matter that does not vary from sample to sample. Includes elements and compounds

31. Classifying Matter by Composition
1-Elements- simplest kind of matter, made of one type of atom
An atom is the smallest unit of an element that maintains the properties of that element.
Cannot be broken down into simpler substances by ordinary chemical means
Ex. gold, copper, oxygen (on the periodic table)

32. Classifying Matter by Composition
2-Compounds – matter composed of the atoms of two or more elements chemically bonded
Compounds can be broken down by chemical methods
When they are broken down, the components have completely different properties than the compound.
Ex. Sugar, salt, water, carbon dioxide

33. Compounds Compounds are also pure substances.
But compounds are made from more than one element.
Water is a compound.
Water can be broken down into simpler substances – hydrogen and oxygen.

34. Classify It
copper wire, aluminum foil

35. Classify It element Magnesium- hetero. mixture Pizza - compound
Homo. (solution)
Examples:
Magnesium-
Pizza -
Calcium chloride
Orange juice
Club soda

36. States of matter
Solid- matter that can not flow and has definite volume and shape
Liquid- definite volume but no definite shape and can flow
Gas- a substance without definite volume or shape and can flow.
Plasma- a substance that is similar to a gas, but loses electrons due to its high temperature

37. States of Matter Definite Volume? Definite Shape?
Particle position and movement
Packed tightly, vibrate about fixed pt
Solid
YES
YES
Close together, can move past each other - flow
Liquid NO
YES
Far apart, move rapidly - flow
Gas NO NO