1. Mixtures, Elements and Compounds
A Matter of Fact
Mixtures, Elements and Compounds

2. Mixtures, Elements and Compounds
Learning Targets:
I will be able to:
distinguish between elements, mixtures, and compounds.
describe ways to separate mixtures into their original components.

3. 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.

4. 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.

5. 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.

6. Scientists ask themselves these questions?
Is the matter uniform throughout?
Can it be separated by physical means?
Can it be separated by chemical means?
By asking these questions scientists can classify matter into:
mixtures: two or more substances that are not chemically combined with each other and can be separated by physical means. The substances in a mixture retain their individual properties.

7. solutions: a special kind of mixture of two or more substances where the molecules or atoms are completely dispersed
elements: simplest form of pure substance that cannot be broken into anything else by physical or chemical means.
compounds: pure substances that are the unions of two or more elements that can be broken into simpler substances by chemical means.
The following flow chart can be used to determine the classification of a substance.

8. But First, 
What is the main difference between a mixture and a compound?
Is toast with cinnamon, sugar, and butter a mixture or a compound? Explain.
Are muffins mixtures or compounds? Explain.
Mixtures can be separated physically, compounds can be separated chemically
Mixture, can be separated physically
Compounds, baking them causes a chemical reaction

10. Is the matter uniform throughout?
If the answer is no, the matter is a heterogeneous mixture: a mixture that is not uniform in composition; components are not evenly distributed.
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.

11. Examples of heterogeneous mixtures
Sand and pebbles
Oil and water
Trail Mix

12. Is it uniform throughout?
If the answer is yes, the matter is homogeneous: of uniform structure or composition throughout
That leads us to another question.
Can it be separated by physical means?
If the answer is yes, the matter is a homogeneous mixture: a mixture that is uniform in composition; components are evenly distributed and not easily distinguished or a solution.

13. Examples of homogeneous mixtures
Chocolate
Coffee
Jell-O
Motor oil
Air

14. Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous mixtures.
They are also colloids: a mixture whose particles are intermediate in size between those of a suspension and a solution

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

16. 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.

17. 
A substance is found to contain Fe (iron) and K (potassium). The substance is heated to 2000C and some of the substance melts. The liquid is poured off and the remaining solid is attracted to a magnet. Is the substance a mixture or a compound? Explain.
How are mixtures and compounds separated into their components?
mixture, separated by physical means
Mixtures by physical means, compounds by chemical means

18. Solutions 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.
The particles in a solution are so small that they never settle out and they can’t be filtered.

19. Special Solutions Not all solutions are liquids.
alloys: are solid solutions of metals and nonmetals that have dissolved in metals
Steel is carbon and other elements dissolved in iron.
Brass is an example of an alloy - it is zinc dissolved in copper.
Gases can be solutions too.
Air is a solution of oxygen and other gases dissolved in nitrogen.

20. Types of solutions Gas Air (oxygen in nitrogen) Liquid
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)

21. Can it be separated by physical means?
If the answer is no, the matter is a pure substance. Pure substances can be either:
an element or
a compound
Elements are the simplest pure substance.
An element can not be changed into a simpler substance by heating or any chemical process.

22. Elements
The smallest particle of an element that has the properties of that element is called an atom.
An atom is the basic building block of matter.
There are more than one hundred known elements in the universe listed on the periodic table of elements.
These elements combine in such a way to create millions of compounds.

23. Elements All elements are made of atoms.
Atoms of the same element are alike.
Atoms of different elements are different.

24. 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.

25.  How are table sugar and table salt similar?
How are table sugar and table salt different?
How are distilled (pure) water and saltwater similar?
How are distilled (pure) water and saltwater different?
Both are white, solid compounds
Sugar is composed of carbon, hydrogen, and oxygen, Salt is composed of sodium and chlorine
Both are clear liquids at room temperature
Distilled water is a compound, saltwater is a mixture

26. Solutes & Solvents
dissolving: is when substances separate and spread evenly throughout the mixture.
solute: the dissolved substance.
solvent: the substance the solute dissolves in
If something is soluble: that means it can dissolve in the solvent
If it is insoluble: it cannot dissolve in the solvent (rocks in water)
Confused yet?

27. The Universal Solvent: Water
Ocean water is basically a water solution that contains many salts.
Body fluids are also water solutions.

28. Water as a solvent
Water is capable of dissolving a variety of different substances.
And, water is called the "universal solvent" because it dissolves more substances than any other liquid.
It is water's chemical composition and physical attributes that make it such an excellent solvent.
Water molecules have a polar arrangement of the oxygen and hydrogen atoms—one side (hydrogen) has a positive electrical charge and the other side (oxygen) has a negative charge.
This allows the water molecule to become attracted to many other different types of molecules.

29. How much are you dissolving?
Concentration is the amount of solute dissolved in the solvent.
A lot of times, it is in grams per milliliter of solvent, or g/mL
Dilute = less solute
Concentrated = more solute
If the solute is colored, then a dilute solution is usually pale, whereas a concentrated solution is dark.
Solubility = The amount of solute needed to make a saturated solution using a given amount of solvent at a certain temperature.

30. Speed it up! There are 3 methods to make a particle dissolve faster:
Mixing - stirring or shaking causes the particles to separate and spread more quickly
Heating - causes particles to move more quickly and separate
Crushing - increases the amount of surface area contact between the solute and solvent and causes better mixing

31. Separating Mixtures
The substances in a mixture are separated by the differences in their physical properties, such as their particle size.
The more different the properties are, the easier it is to separate the substances.
Physical separation techniques:
decanting
distillation
filtration
chromatography

32. Separating Mixtures
decanting: to gently pour off a liquid without disturbing the sediment or the lower liquid layers
distillation: a process used to separate dissolved solids from a liquid, which is boiled to produce a vapor that is then condensed back into a liquid
filtration: a process that separates particles with a filter, blocking larger particles and letting smaller particles or liquids pass through
chromatography: a process in which a chemical mixture is separated into components by seeping through an adsorbent material into separate layers

33. 
How would you separate a mixture of KCl (potassium chloride) dissolved in H2O?
How would you separate sea shells from the sand?
If you were in a hurry while preparing a mixture, how could you speed up dissolving the substance in H2O?
In a solution of sweetened ice tea, what is the solute and what is the solvent?
Distillation
Filtration
Mixing, heating, or crushing
Solute = sugar, solvent = tea