classification of matter. every sample of matter can be classified as a: pure substance element...

Classification of Matter

Every sample of matter can be classified as a:

Pure Substance

• Element• Molecule

– Diatomic molecule

• Compound

Mixture

• Homogeneous– Solution

• Heterogeneous– Colloid– Suspension

Pure Substances

• Pure Substances cannot be broken down into any other substances by physical means

Gold - element Manganese Dioxide - compound

Pure Substance

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

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

Molecules

• Groups of two or more atoms bound by chemical bonds

• Can be two of the same element

Pure Substances


Sodium Chloride – NaCl (Table Salt)

Sodium (Na) - Metal Chlorine (Cl) - gas Sodium Chloride NaCl

Fixed ratio: 1 Na for every 1 ClSodium in water video

http://www.youtube.com/watch?v=ODf_sPexS2Q

Pure Substances - FYILaw of Definite CompositionLaw of Definite Composition

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


Two different compounds, each has a definite composition

Diatomic Elements, 1 and 7H2

N2 O2 F2

Cl2

Br2

I2

Diatomic molecules are molecules composed only of two atoms, of the same

elements. The prefix di- means two in Greek. Common diatomic molecules are

hydrogen (H2), nitrogen (N2), oxygen (O2), Fluorine (F), Chlorine (Cl), Bromine (Br), and

Iodine (I).

Chemical Formulas

Shows the compound and the ratio of atoms

Mixtures Variable combination of two or more

pure substances. Each keep individual properties

Homogeneous- Evenly Mixed cannot see different parts. (Same)

Heterogeneous – Can see different parts (different)


Tyndall Effect

• The scattering

of light by particles

in a mixture

• http://www.youtube.com/watch?v=gheuYqQ6phE&feature=related

Mixtures

Solution– homogeneous– very small particles– no Tyndall effect– particles don’t settle

– Examples: – rubbing alcohol

(ethyl alcohol and water)– Air

(nitrogen and oxygen)

MixturesColloid

– heterogeneous– medium-sized particles– Tyndall effect– particles don’t settle– Particles scatter light– EX:

• Milk• Clouds• Smoke• mayo


Mixtures

Suspension– heterogeneous– large particles– Tyndall effect– particles settle– EX:

• fresh-squeezed lemonade

• Sand in water


MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

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

atoms

oxygen atoms

Consider Concentration Here!

Elementsonly one kind

of atom; atomsare bonded ifthe element

is diatomic orpolyatomic

Compounds

two ormore kindsof atoms

that are chemicallybonded

substancewith

definitemakeup

andproperties

Mixturestwo or moresubstances

that arephysically

mixed

Both elements and compounds have a definite makeup and definite properties.


uniformproperties?

fixedcomposition?

chemicallydecomposable?

no

no

no

yes

hetero-geneousmixture

solution

element

compound

http://antoine.frostburg.edu/chem/senese/101/matter/slides/sld003.htm

Compounds vs. Mixtures

• Compounds have properties that are uniquely different from the elements from which they are made. – A formula can always be written for a compound

– e.g. NaCl Na + Cl2

• Mixtures retain their individual properties.– e.g. Salt water is salty and wet


MATTER(gas. Liquid,

solid, plasma)

PURESUBSTANCES MIXTURES

HETEROGENEOUSMIXTURE

HOMOGENEOUSMIXTURESELEMENTSCOMPOUNDS

Separated by

physical means into

Separated by

chemical means into

Kotz & Treichel, Chemistry & Chemical Reactivity, 3rd Edition , 1996, page 31

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


Mixture vs. Compound

Mixture

FixedComposition

Bonds between

components

Can ONLY beseparated by

chemical means

VariableComposition

No bondsbetween

components

Can beseparated by

physical means

Alike Different

Contain two or more

elements

Can beseparated

intoelements

Involvesubstances

Compound

Different

Topic Topic

Top Ten Elements in the Universe

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)

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 26

The Composition of Air

AirAir

NitrogenNitrogen

OxygenOxygenHeliumHelium

Watervapor

Watervapor

NeonNeon

Carbondioxide

Carbondioxide ArgonArgon

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 34

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:

N2

O2

H2O

Ar

CO2

Ne

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

Matter Flowchart

Examples:

– graphite

– pepper

– sugar (sucrose)

– paint

– soda


element

hetero. mixture

compound

solution homo. mixture

hetero. mixture

Mixtures

Examples:

– mayonnaise

– muddy water

– fog

– saltwater

– Italian salad dressing


colloid

suspension

colloid

solution

suspension

Reviewing ConceptsReviewing 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?

Separating a Mixture


• Chromatography - To separate different colored dyes. The dyes travel up the chromatography paper at different distances before they cannot remain in solution. The more soluble dyes move further up than the less soluble ones, hence separating from each other.


• Distillation - to separate and collect a liquid from a solution of a soluble solid. The solution is heated in a flask until the liquid boils. The vapor produced passes into the condenser where it is cooled and condenses to a liquid. The pure liquid (distillate) is collected in a beaker.


Evaporation –

This method is suitable to separate a soluble solid from a liquid. If the solution is heated, the liquid evaporates leaving the solid behind.


Fractional Distillation - This is a special type of distillation used to separate a mixture of liquids. Different liquids boil at different temperatures. When heated, they boil off and condense at different times. The apparatus features a fractionating column, which ensures that only the liquid boils at its boiling point will pass into the condenser.


Filtration –

To separate an insoluble solid from a liquid. The solid remains in the filter paper and the liquid goes through the paper into the beaker.

classification of matter. every sample of matter can be classified as a: pure substance element...

Documents

different compounds

fixed ratio of elements

definite properties

definite makeup

definite compositiona

common diatomic molecules

alcohol ethyl alcohol

nitrogen n2