Transcript Classifying Matter

Classifying Matter
• Scientists classify matter according to make-up.
Matter
Elements
Compounds
Mixtures
Elements
• 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 Key
Atomic Number
Symbol
I.D’s the element
represents elements
Element Name
Atomic Mass
mass of element (amu’s)
Elements/Symbols
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Calcium
Tin
Uranium
Magnesium
Phosphorus
Iron
iodine
Silver
Helium
Mercury
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Nickel
Silicon
Sulfur
Copper
Chromium
Aluminum
Bromine
Hydrogen
Zinc
Potassium
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Oxygen
Lead
Lithium
Gold
Fluorine
Neon
Nitrogen
Sodium
Carbon
Chlorine
Compounds
• 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 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 H2 O
Identifying Substances
Element
or
Compound
Symbol
or
Formula
Atom
or
Molecule
Fluorine (F)
Element
Symbol
Atom
Water (H2O)
Compound
Formula
Molecule
Chlorine gas
(Cl2)
Element
Formula
Molecule
Substance
Counting Atoms
Name
Calcium
carbonate
Magnesium
hydroxide
Use
Formula
Chalk
CaCO3
Found in
milk of
magnesia
Mg(OH)2
Atoms in
Formula
Ca=1
C=1
O=3
Mg=1
O=2
H=2
H=9
P=3
Phosphoric
acid
Detergents
Trinitrotoluene
(TNT)
Explosive 2C7H5(NO2)3 C=14 N=6
3H3PO4
O=12
H=10 O=12
Calculating Formula Mass
• Formula mass of a compound is the sum of the atomic
weights of all atoms in a chemical formula.
• Examples:
H 2O
Atoms
Atomic Mass
Totals
2 of H
2 x 1.0
2.0
1 of O
1 x 16.0
16.0
18.0 amu
C12H22O11 12 of C
12 x 12.0
144.0
22 of H
22 x 1.0
22.0
11 of O
11 x 16.0
176.0
342.0 amu
Mixtures
• 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.
Mixtures
Mixtures
Homogeneous
Heterogeneous
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 Mixtures
• Well-mixed. Same
throughout a given
sample.
• Examples: air,
soda, toothpaste,
lotions, etc.
Solutions
• A homogeneous mixture.
• One substance dissolves in another.
Solutions remain constantly & uniformly
mixed.
• Examples: lemonade, soda, ocean water,
antifreeze, metal alloys (steel, brass), etc.
Colloids
• A homogeneous mixture.
• Mixed together but not dissolved.
• Appears cloudy. Scatters light.
• Examples: milk, cool whip, toothpaste, lotions,
fog, paint, etc.
Composition of Matter
Matter
Pure Substance
Element
Compound
Mixture
Homogeneous
Solution
Colliod
Heterogeneous
Suspension