Matter
Types…And Changes
CHM 1010
PGCC
Barbara A. Gage
Matter
• Mixture – material with two or more
components with variable composition
• Solution – material with two or more
components homogeneously mixed; can
have variable proportions of the
components
• Pure substance – material with a
constant chemical composition
Physical Separation Techniques
•
•
•
•
•
•
•
•
What property is each technique based
on?
Dissolving
Evaporating (evaporation)
Filtering (filtration)
Chromatography
Sieving sifting straining
Subliming (sublimation)
Distilling (distillation)
Extracting (extraction)
CHM 1010
PGCC
Barbara A. Gage
Types of Matter
• Element - the simplest type of
substance with unique physical and
chemical properties. It cannot be
broken down into any simpler substances
by physical or chemical means.
• Compound - a substance composed of
two or more elements which are
chemically combined.
Figure 2.19
The distinction between mixtures and compounds.
Silberberg
S
Fe
Physically mixed therefore can be
separated by physical means; in this
case by a magnet.
Allowed to react chemically
therefore cannot be separated
by physical means.
CHM 1010
PGCC
Barbara A. Gage
Types of Matter
• Atom – smallest unit of an element with
all the characteristics of the element
Types of Matter
• Molecule - a structure that consists of
two or more atoms that are chemically
bound together and thus behaves as an
independent unit; smallest
characteristic unit of a compound that
retains the properties of the compound
Figure 2.1
Silberberg
The boxes here contain
submicroscopic views of
particles. Indicate
which box(es) contain
the stated item(s) and
why.
a.only elements
b.one compound
c.mixture of compounds
d.molecules
a.
b.
c.
d.
B, C, E
A (plus an element), D
F
All but E
Element Names and Symbols
• Each element has a name and 1, 2 or 3
letter abbreviation called a symbol. The
first letter in a symbol MUST be capital
and the other(s) lowercase.
•
•
•
•
hydrogen
carbon
sodium
lead
H
C
Na
Pb
helium
He
cobalt
Co
potassium K
mercury Hg
Image from WebElements
Element Names and Symbols
• Number of elements – 117 (#117 has not
been identified but 118 has)
CHM 1010
PGCC
Barbara A. Gage
Chemical Formulas
• Some elements appear in nature bonded
to each other. These are referred to
as diatomic or polyatomic molecules.
H2, O2, N2, F2, Cl2, Br2, I2
C60, S8, P4
• The 2 in O2 is termed a subscript and
refers to the element immediately in
front of it.
Chemical Formulas
• CO2 contains 1 atom of carbon and two
atoms of oxygen all chemically linked.
• H2SO4 contains 2 hydrogen, 1 sulfur,
and 4 oxygen atoms.
• (NH4)2C2O4 - A subscript outside
parentheses applies to everything within
the parentheses; 2 N, 8 H, 2 C, 4 O
Chemical Formulas
• How many atoms of each type are in the
following compounds?
• K2CO3
• Ca3(PO4)2
• C6H4COOHCOC2H5
• AlK(SO4)2.12H2O
Chemical Reaction
• Chemical change = chemical reaction
Changes may be visible:
• color change
• cloudiness (precipitation)
• gas formed (bubbles and/or odor)
• reactant decreases (without dissolving)
• energy is released or absorbed
Chemical Equations
• Chemical changes can be written
symbolically. The symbolic
representation is called a chemical
equation.
Carbon reacts with oxygen to form carbon
dioxide.
C + O2  CO2
reactants
products
Chemical Equations
• Reaction arrows can go in either
direction:
2 H2 + O2

2 H2O
• Or both directions:
NH4OH
 NH3 + H2O
Or…
Chemical Equations
• Because of the Law of Conservation of
Matter, you must account for all atoms
in a chemical change.
Carbon reacts with oxygen to form carbon
monoxide.
C
+ O2 
CO
2C
+ O2  2 CO
Equation is now balanced.
coefficient
Chemical Equations
• A sample of propane, C3H8, when ignited
with oxygen produces carbon dioxide
and water.
C3H8
+
O2 
C3H8
+ 5 O2 
CO2 + H2O
3 CO2 + 4 H2O
Chemical Equations
• Balance the following:
CaCl2
+ Na2CO3  NaCl + CaCO3
C3H8O2 +
H2SO4
O2 
+
CO2 + H2O
KOH  K2SO4 + H2O
Chemical Equations
• If you have information on the states of
matter, that can be added to the
equation.
s = solid l = liquid g = gas aq = aqueous
Aqueous silver nitrate reacts with
aqueous potassium chloride to form
solid silver chloride and aqueous
potassium nitrate.
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)
Before
• Write the balanced
chemical equation
for the change in
the boxes.
After
Balancing Tips…
• Balance polyatomic ions (units) that stay
intact as a single unit.
• Leave hydrogens and oxygens to the last
(oxygen very last).
• Be sure to reduce the coefficients to
the smallest whole numbers.
Types of Reactions
• 1) Combination or Synthesis
• elements or (element + compound) or
compounds ------> compound
•
Fe (s) +
S (s) ------> FeS (s)
•
O2 (g) + 2 CO (g) ------> 2 CO2 (g)
•
H2O (l) + SO3 (g) ------> H2SO4 (aq)
Types of Reactions
• 2) Decomposition or Analysis
• compound ------> elements or (element
and compound) or compounds
•
2 HgO (s) -----> 2Hg (l) + O2 (g)
•
2 KBrO3 (s) -----> 2 KBr (s) + 3 O2 (g)
•
CaCO3 (s) ------> CaO (s) + CO2 (g)
Types of Reactions
• 3) Single Replacement
element + compound -------->
element + compound
• Cu (s) + 2AgNO3 (aq) ---->
2Ag (s) + Cu(NO3)2 (aq)
•
Types of Reactions
• 4) Double Replacement
compound + compound —> compound +compound
AgNO3 (aq) + NaCl (aq) —> AgCl (s) +NaNO3 (aq)
Double Replacement Rxns:
Solid forming
AgNO3 (aq) + NaCl (aq) —> AgCl (s) +NaNO3 (aq)
Gas-forming
KHCO3 (aq) + HCl (aq) ----> KCl (aq) + CO2 (g) +H2O (l)
Acid-Base
HCl (aq) + KOH (aq) ----> KCl (aq) + H2O (l)
Types of Reactions
• 5) Oxidation-Reduction (redox)
CH4 (g) + 2O2 (g) ----> CO2 (g) + 2H2O (l)
2Mg (s) + O2 (g) -----------> 2MgO (s)
4HCl (aq) + 3FeCl2 (aq) + KMnO4(aq) -->
MnO2(s) + KCl(aq) + 3FeCl3(aq) + 2H2O(l)
Investigation of Chemical
Reactions
• Let’s finish the lab by writing the
balanced chemical equations and
determining the reaction types:
1. Mg + HCl
2. Mg (heat)
3. CoCl2 + Na3PO4
4. Fe + CuSO4
5. KClO3 (heat)
6. CuCO3 (heat)