Classification of Matter. Pure Substances Element –composed of identical atoms –EX: copper wire,...

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Classification of Matter

Pure Substances

Element– composed of identical atoms– EX: copper wire, aluminum foil

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

Pure Substances

Compound

– composed of 2 or more elements in a fixed ratio

– properties differ from those of individual elements

– EX: table salt (NaCl)

Pure Substances

Law of Definite CompositionLaw of Definite Composition

– A given compound always contains the same, fixed ratio of elements.

Law of Multiple ProportionsLaw of Multiple Proportions

– Elements can combine in different ratios to form different compounds.

Pure Substances

For example…

Two different compounds, each has a definite composition.

Carbon, C Oxygen, O Carbon monoxide, CO

Carbon, C Oxygen, O Oxygen, O Carbon dioxide, CO2

MATTER

Can it be physically separated?

Compound Element

PURE SUBSTANCE

Can it be chemically decomposed?

Mixtures

Variable combination of 2 or more pure substances.

Heterogeneous Homogeneous

Mixtures

Solution– homogeneous– very small particles– no Tyndall effect Tyndall Effect

– particles don’t settle– EX: rubbing alcohol

Mixtures

Colloid– heterogeneous– medium-sized particles– Tyndall effect– particles don’t settle– EX: milk

Mixtures

Suspension– heterogeneous– large particles– Tyndall effect– particles settle– EX: fresh-squeezed

lemonade

Classification of Matter

Materials

HomogeneousHeterogeneous

Heterogeneousmixture

Homogeneousmixture

Substance

Element Compound Solution Mixture

Order / Disorder

Smoot, Smith, Price, Chemistry A Modern Course, 1990, page 43

MATTER

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

noyesIs the composition uniform?

Colloids Suspensions

Elements, Compounds, and Mixtures

(a)an element(hydrogen)

(b)a compound(water)

(c)a mixture(hydrogen and oxygen)

(d)a mixture(hydrogenand oxygen)

Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68

hydrogenatoms hydrogen

oxygen atoms

Matter Flowchart

Examples:

– graphite

– pepper

– sugar (sucrose)

– paint

– soda

element

hetero. mixture

compound

hetero. mixture

solution

Elements, Compounds, and Mixtures

(a)an element(hydrogen)

(b)a compound(water)

(c)a mixture(hydrogen and oxygen)

(d)a mixture(hydrogenand oxygen)

Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68

hydrogenatoms hydrogen

oxygen atoms

Matter

MatterMatter

SubstanceDefinite composition

(homogeneous)

SubstanceDefinite composition

(homogeneous)

Element(Examples: iron, sulfur,

carbon, hydrogen,oxygen, silver)

Element(Examples: iron, sulfur,

carbon, hydrogen,oxygen, silver)

Mixture ofSubstances

Variable composition

Mixture ofSubstances

Variable composition

Compound(Examples: water.

iron (II) sulfide, methane,Aluminum silicate)

Compound(Examples: water.

iron (II) sulfide, methane,Aluminum silicate)

Homogeneous mixtureUniform throughout,also called a solution

(Examples: air, tap water,gold alloy)

Homogeneous mixtureUniform throughout,also called a solution

(Examples: air, tap water,gold alloy)

Heterogeneous mixtureNonuniform

distinct phases(Examples: soup, concrete, granite)

Heterogeneous mixtureNonuniform

distinct phases(Examples: soup, concrete, granite)

Chemicallyseparable

Physicallyseparable

The Organization of Matter

MATTER

PURESUBSTANCES

HETEROGENEOUSMIXTURE

HOMOGENEOUSMIXTURES

ELEMENTS COMPOUNDS

Physical methods

Chemical methods

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 41

Top Ten Elements in the Universe

Percent

Element (by atoms) 1. Hydrogen 73.92. Helium 24.03. Oxygen 1.14. Carbon

0.465. Neon 0.136. Iron 0.117. Nitrogen

0.0978. Silicon 0.0659. Magnesium 0.05810.Sulfur 0.044

A typical spiral galaxy(Milky Way is a spiral galaxy)

The Composition of Air

AirAir

NitrogenNitrogen

OxygenOxygenHeliumHelium

Watervapor

NeonNeon

Carbondioxide

Carbondioxide ArgonArgon

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 twohydrogen atoms and one oxygen atom:

Argon consists of individual argon atoms:

Carbon dioxide consists of molecules consistingof two oxygen atoms and one carbon atom:

Neon consists of individual neon atoms:

Helium consists of individual helium atoms:

HeZumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 35

Reviewing ConceptsClassifying 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?

MATTER

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

noyesIs the composition uniform?

Colloids Suspensions

Classification of Matter. Pure Substances Element –composed of identical atoms –EX: copper wire,...

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