Classification of Matter. Every sample of matter can be classified as a: Pure Substance Element...
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Transcript of 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
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Molecules
• Groups of two or more atoms bound by chemical bonds
• Can be two of the same element
Pure Substances
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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
Pure Substances - FYILaw of Definite CompositionLaw of Definite Composition
– A given compound always contains the same, fixed ratio of elements.
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
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)
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
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
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Mixtures
Suspension– heterogeneous– large particles– Tyndall effect– particles settle– EX:
• fresh-squeezed lemonade
• Sand in water
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
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
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
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.
Classification of Matter
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
Classification of Matter
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
Classification of Matter
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
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
element
hetero. mixture
compound
solution homo. mixture
hetero. mixture
Mixtures
Examples:
– mayonnaise
– muddy water
– fog
– saltwater
– Italian salad dressing
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
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
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.
Separating a Mixture
• 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.
Separating a Mixture
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.
Separating a Mixture
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.
Separating a Mixture
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.