classifying matter matter elementscompoundsmixtures scientists classify matter according to make-up
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Classifying MatterClassifying Matter
Matter
ElementsCompound
sMixtures
• Scientists classify matter according to make-up.
ElementsElements
• Simplest pure substance – fixed composition.
• Pure substance is made of only one material. Same throughout. Referred to as homogeneous matter.
• Are made of alike atoms, which are the basic building blocks of matter.
• Represented by chemical symbols - H, O, Al, Cu, Au.
• 118 elements organized in the periodic table in squares called an element key.
Element KeyElement Key
Atomic Number
Symbol
Element Name
Atomic Mass
I.D’s the element
represents elements
mass of element (amu’s)
• Calcium• Tin• Uranium• Magnesium• Phosphorus• Iron• iodine• Silver• Helium• Mercury
• Nickel• Silicon• Sulfur• Copper• Chromium• Aluminum• Bromine• Hydrogen• Zinc• Potassium
Elements/Symbols Elements/Symbols
• Oxygen• Lead• Lithium• Gold• Fluorine• Neon• Nitrogen• Sodium• Carbon• Chlorine
CompoundsCompounds
• Two or more elements chemically combined.
• Represented by chemical formulas.
• Examples: H2O, CO2, NaCl, C12H22O11
• Molecules are the smallest natural unit of a compound or diatomic element. A molecule is made up of two or more atoms chemically combined.
Chemical FormulasChemical Formulas• Combination of chemical symbols that represents compounds.
• Sometimes represents a molecule of an element. Example: O2, N2, Cl2 called diatomic elements – two atoms of the same element.
• Subscripts are the # of atoms of an element - H2O
• Coefficients are the # placed in front of chemical formula. Represents # of molecules of a compound - 4 H2O
Identifying SubstancesIdentifying Substances
Substance
Element or
Compound
Symbol or
Formula
Atom or
Molecule
Fluorine (F)
Water (H2O)
Chlorine gas (Cl2)
Element Symbol
Atom
Compound
Formula
Formula
Molecule
Element
Molecule
Counting AtomsCounting Atoms
Name Use FormulaAtoms in Formula
Calcium carbonate
Chalk CaCO3
Magnesium hydroxide
Found in milk of
magnesia
Mg(OH)2
Phosphoric acid
Detergents
3H3PO4
Trinitrotoluene (TNT)
Explosive
2C7H5(NO2)3
Ca=1C=1O=3
H=9
P=3
O=12
Mg=1
O=2
H=2
C=14 N=6
H=10 O=12
Calculating Formula Mass
Calculating Formula Mass
• Formula mass of a compound is the sum of the atomic weights of all atoms in a chemical formula.
• Examples: Atoms Atomic Mass Totals
H2O 2 of H 2 x 1.02.0
1 of O 1 x 16.016.0
18.0 amu
C12H22O11 12 of C 12 x 12.0144.0
22 of H 22 x 1.0 22.0
11 of O 11 x 16.0 176.0
342.0 amu
MixturesMixtures
• Two or more substances mixed together but not chemically combined.
• Has unlike parts and a composition that varies from sample to sample.
• Properties:
– Sub. in a mixture keep their separate identities.
– Sub. can be present in any amount.
– Sub. can be separated out by physical means.
Heterogeneous Mixtures
Heterogeneous Mixtures
• The least-mixed.• Doesn’t appear to
be the same throughout.
• Particles large enough to be seen.
• Examples: sand, dirt, concrete, suspensions, etc.
Homogeneous MixturesHomogeneous Mixtures
• Well-mixed. Same throughout a given sample.
• Examples: air, soda, toothpaste, lotions, etc.
SolutionsSolutions
• A homogeneous mixture.
• One substance dissolves in another. Solutions remain constantly & uniformly mixed.
• Examples: lemonade, soda, ocean water, antifreeze, metal alloys (steel, brass), etc.
ColloidsColloids
• A homogeneous mixture.
• Mixed together but not dissolved.
• Appears cloudy. Scatters light.
• Examples: milk, cool whip, toothpaste, lotions, fog, paint, etc.