Classification of Matter

ObjectivesClassify matter as a pure substance or

a mixtureExplain the difference between an

element and a compoundDistinguish between homogeneous

and heterogeneous mixturesDescribe three ways that components

of mixtures can be separatedContract pure substances and

mixtures

Important Vocabulary

Pure substance

ElementCompoundChemical

symbolMixtureHeterogeneousHomogenous

SolutionSolventSoluteAqueous solutionAlloyChemical

FormulaFiltration Distillation

Is matter that has definite chemical and physical properties

There are two types of pure substances:◦Elements◦Compounds

Pure Substances

Is the simplest form of matter that has a unique set of properties

They can NOT be broken down into simpler substances by chemical means

Examples?How elements are in the Periodic Table?How many of them have official names?They have distinct chemical symbols

Element

118114

Chemical SymbolsAre used to represent elementsChemical symbol is a one-letter or two-

letter codeThe first letter is always capitalized and

the second letter must be lowercase.They have been around since ancient time in

various formats The symbols used today are based on a

system developed by Swedish chemist, Jons Jacob Berzelius

He based his system on the Latin names of elements.

Jons Jacob Berzelius

1779 –1848

Latin Named Elements

Other Element Name Origins

Is a substance that contains two or more elements chemically combined in a fixed proportion

Compounds have characteristic properties and compositions

They can be broken down into their elements by chemical means

They are represented by formulas, which is a group of chemical symbols that shows the type of elements and their amount in a compound

Examples?

Compound

Properties of Compounds In general, the properties of compounds

are quite different from those of their component elements

For example: Sucrose C12H22O11(table sugar)◦Elements: Carbon, Hydrogen & Oxygen

Carbon- is black, tasteless solid Hydrogen- is a colorless, odorless gas,

explosive with a spark Oxygen-is a colorless odorless gas,

essential for lifeProperties of Sucrose?How about salt? (NaCl)

Are a combination of two or more pure substances physically combined

The proportions of the ingredients can varyThe properties of mixtures can change as

wellFor example: salad, Kool-Aid, concrete, air,

& alloysAn alloy is a mixture of metals in various

proportions to influence density, color, and strength (Table 1 p.23)

Mixtures can be classified in two ways

Mixtures

Heterogeneous MixturesAre mixtures that do NOT have

a uniform composition throughout (unevenly mixed)

Examples:◦Water & Flour◦Sand & Salt◦Salad ◦Chocolate chip cookie dough

Different regions of this type of mixture have different properties

Homogeneous MixturesAre mixtures that have a

uniform structure or composition throughout

Examples:◦Gasoline◦Syrup◦Air◦Vinegar◦Tomato soup

Properties are also uniform throughout the mixtures

Also called a solution

SolutionsAre homogeneous mixturesMost are liquidsEach solution has two parts:A solute, which is the substances that is dissolvedA solvent, which is the substance that does the

dissolvingIf the solvent is water, it is called an aqueous

solutionExamples:

◦ Rubbing alcohol◦ Saltwater◦ Air◦ Stainless steel

PhasesIs used to describe any

part of sample with uniform composition and properties

Homogeneous mixtures consist of one phase

Heterogeneous mixtures consist of two or more phases

For example: oil and water mixture

Some mixtures are easier to separate than others

Differences in physical properties can be used to separate mixtures

Techniques for separation include◦Filtration◦Distillation◦Chromatography

Separating Mixtures

FiltrationIs the process

that separates a solid from the liquid in a heterogeneous mixture

For example: making coffee & straining pasta

DistillationIs the process where a liquid is

boiled to produce a vapor that is then condensed into a liquid

For example: distilling water to remove minerals

In this case, the solid substances that were dissolved in the water remain in the distillation flask because their boiling points are much higher than water’s boiling point

Distillation Apparatus

ChromatographyThe mixture is dissolved in a

fluid called the mobile phase, which carries it through a structure holding another material called the stationary phase. 

The various constituents of the mixture travel at different speeds, causing them to separate.

Breaking Down CompoundsPhysical separation methods used

for mixtures do not work for compounds

Because compounds are chemically combined, they require a chemical change to be broken down

Pure SubstancesAre elements or

compoundsChemically

combinedProperties of

compounds are different from their individual components

Its components are in definite proportions or fixed

Are HOG or HEDPhysically

combinedProperties of

mixtures are reflected by their components

Its composition can be in varying proportions

Distinguishing Pure Substances & Mixtures

Mixtures