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
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Pure Substances
Compound
– composed of 2 or more elements in a fixed ratio
– properties differ from those of individual elements
– EX: table salt (NaCl)
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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.
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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
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MATTER
Can it be physically separated?
Compound Element
PURE SUBSTANCE
no
Can it be chemically decomposed?
noyes
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Mixtures
Variable combination of 2 or more pure substances.
Heterogeneous Homogeneous
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Mixtures
Solution– homogeneous– very small particles– no Tyndall effect Tyndall Effect
– particles don’t settle– EX: rubbing alcohol
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Mixtures
Colloid– heterogeneous– medium-sized particles– Tyndall effect– particles don’t settle– EX: milk
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Mixtures
Suspension– heterogeneous– large particles– Tyndall effect– particles settle– EX: fresh-squeezed
lemonade
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Classification of Matter
Materials
HomogeneousHeterogeneous
Heterogeneousmixture
Homogeneousmixture
Substance
Element Compound Solution Mixture
Speci
fic /
Gen
eral
Order / Disorder
Smoot, Smith, Price, Chemistry A Modern Course, 1990, page 43
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
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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
Matter Flowchart
Examples:
– graphite
– pepper
– sugar (sucrose)
– paint
– soda
element
hetero. mixture
compound
hetero. mixture
solution
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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
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
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
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
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
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