A Matter of FactA Matter of Fact

Mixtures, Elements and Mixtures, Elements and CompoundsCompounds

Mixtures, elements, compoundsMixtures, elements, compounds

Scientists like to classify things.Scientists like to classify things. One way that scientists classify matter is One way that scientists classify matter is

by its composition.by its composition. Ultimately, all matter can be classified as Ultimately, all matter can be classified as

mixtures, elements and compounds.mixtures, elements and compounds.

Why isn’t it a good idea to Why isn’t it a good idea to classify matter by its phases?classify matter by its phases?

Because one kind of substance can exist in more than Because one kind of substance can exist in more than one phase – such as Hone phase – such as H220. And matter changes phases 0. And matter changes phases rather easily.rather easily.

Why isn’t matter classified Why isn’t matter classified according to its physical according to its physical

characteristics, such as color?characteristics, such as color?

Scientists wouldn’t find it very useful to group Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together.gold, sunflowers, and the sun together.

Scientists ask themselves these Scientists ask themselves these questions?questions? Is the matter uniform throughout?Is the matter uniform throughout? Can it be separated by physical means?Can it be separated by physical means? Can it be separated by chemical means?Can it be separated by chemical means?

By asking these questions scientists can classify By asking these questions scientists can classify matter into:matter into:

MixturesMixtures – two or more substances that are not – two or more substances that are not chemically combined with each other and can be chemically combined with each other and can be separated by physical means. The substances in separated by physical means. The substances in a mixture retain their individual properties.a mixture retain their individual properties. Solutions – a special kind of mixture where one Solutions – a special kind of mixture where one

substance dissolves in another.substance dissolves in another. ElementsElements – simplest form of pure substance. – simplest form of pure substance.

They cannot be broken into anything else by They cannot be broken into anything else by physical or chemical means.physical or chemical means.

CompoundsCompounds – pure substances that are the – pure substances that are the unions of two or more elements. They can be unions of two or more elements. They can be broken into simpler substances by chemical broken into simpler substances by chemical means.means.

Is it uniform throughout?Is it uniform throughout?

If the answer is no, the matter is a If the answer is no, the matter is a heterogeneous mixture.heterogeneous mixture. Considered the “least mixed.”Considered the “least mixed.” Does not appear to be the same throughout.Does not appear to be the same throughout. Particles are large enough to be seen and to Particles are large enough to be seen and to

be separated from the mixture.be separated from the mixture.

Examples of heterogeneous Examples of heterogeneous mixturesmixtures

Sand and pebblesSand and pebbles Oil and waterOil and water Powdered iron and powdered sulfurPowdered iron and powdered sulfur

Granite is a heterogeneous mixture.

Is it uniform throughout?Is it uniform throughout?

If the answer is yes, the matter is If the answer is yes, the matter is homogeneous (looks the same homogeneous (looks the same throughout).throughout).

That leads us to another question.That leads us to another question.

Can it be separated by physical Can it be separated by physical means?means?

If the answer is yes, the matter is a If the answer is yes, the matter is a homogeneous mixture or solution.homogeneous mixture or solution.

Homogeneous MixturesHomogeneous Mixtures

A mixture that appears to be the same A mixture that appears to be the same throughout.throughout.

It is “well mixed.”It is “well mixed.” The particles that make up the mixture are The particles that make up the mixture are

very small and not easily recognizable.very small and not easily recognizable.

Examples of homogeneous Examples of homogeneous mixturesmixtures

Milk, toothpaste, and mayonnaise are homogeneousmixtures. They are also colloids.

ColloidsColloids

In a colloid the In a colloid the particles are mixed particles are mixed together but not together but not dissolved.dissolved.

The particles are The particles are relatively large and relatively large and are kept permanently are kept permanently suspended.suspended.

0

20

40

60

80

100

1st

Qtr

2nd

Qtr

3r d

Qtr

4th

Qtr

East

West

North

ColloidsColloids

A colloid will not A colloid will not separate upon separate upon standing.standing.

The particles are The particles are constantly colliding, constantly colliding, and this allows a and this allows a colloid to scatter light colloid to scatter light – thus colloids often – thus colloids often seem cloudy.seem cloudy.

SolutionsSolutions

A solution is a type of homogeneous mixture A solution is a type of homogeneous mixture formed when one substance dissolves in formed when one substance dissolves in another.another.

It is the best mixed of all mixtures.It is the best mixed of all mixtures. A solution always has a substance that is A solution always has a substance that is

dissolved and a substance that does the dissolved and a substance that does the dissolving.dissolving.

The substance that is dissolved is the solute and The substance that is dissolved is the solute and the substance that does the dissolving is the the substance that does the dissolving is the solvent.solvent.

Ocean water is a solutionOcean water is a solution

The universal solvent: WaterThe universal solvent: Water

Water as a solventWater as a solvent

Many liquid solutions contain water as the Many liquid solutions contain water as the solvent.solvent.

Ocean water is basically a water solution Ocean water is basically a water solution that contains many salts.that contains many salts.

Body fluids are also water solutions.Body fluids are also water solutions.

Types of solutionsTypes of solutions

GasGas GasGas Air (oxygen in nitrogen)Air (oxygen in nitrogen)GasGas LiquidLiquid Soda water (carbon dioxide in Soda water (carbon dioxide in

water)water)SolidSolid LiquidLiquid Ocean water (salt in water)Ocean water (salt in water)

Solute Solvent Example

SolidSolid SolidSolid Gold jewelry Gold jewelry (copper in gold)(copper in gold)

Metals dissolved in metals are called

alloys.

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

AlloysAlloys

Brass is an alloy of copperand zinc.

Stainless steel is a mixtureof iron and chromium.

Can it be separated by physical Can it be separated by physical means?means?

If the answer is no, the matter is a pure If the answer is no, the matter is a pure substance.substance. An elementAn element Or a compoundOr a compound

ElementsElements

Elements are the simplest pure substance.Elements are the simplest pure substance. An element can not be changed into a simpler An element can not be changed into a simpler

substance by heating or any chemical process.substance by heating or any chemical process. The smallest particle of an element that has the The smallest particle of an element that has the

properties of that element is called an atom.properties of that element is called an atom. An atom is the basic building block of matter.An atom is the basic building block of matter.

There are more than one hundred known There are more than one hundred known elements in the universe listed on the periodic elements in the universe listed on the periodic table of elements.table of elements. These elements combine in such a way to create These elements combine in such a way to create

millions of compounds.millions of compounds.

ElementsElements

All elements are All elements are made of atoms.made of atoms.

Atoms of the same Atoms of the same element are alike.element are alike.

Atoms of different Atoms of different elements are elements are different.different.

ElementsElements

In 1813, a system In 1813, a system of representing of representing elements with elements with symbols was symbols was introduced.introduced. Each symbol consists of one Each symbol consists of one

or two letters.or two letters. Two letters are needed for a Two letters are needed for a

chemical symbol when the first chemical symbol when the first letter of that element’s name letter of that element’s name has already been used.has already been used.

Common ElementsCommon Elements

AluminumAluminum AlAlBromineBromine BrBrCalciumCalcium CaCaCarbonCarbon CCGoldGold AuAuHeliumHelium HeHeHydrogenHydrogen HHNitrogenNitrogen NN

CompoundsCompounds

Compounds are also Compounds are also pure substances.pure substances.

But compounds are But compounds are made from more than made from more than one element.one element.

Water is a compound.Water is a compound. Water can be broken Water can be broken

down into simpler down into simpler substances – substances – hydrogen and hydrogen and oxygen.oxygen.