Exam R 12 pm

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Exam R 12 pm Review T 2 SL120. NO GRAPHING
CALULATORS!!!!!!!!!
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Figure 2.16 Molecular and structural formulas
and molecular models.
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Ethanol
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Fig. 2.18
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Figure 2.19 A model of a portion of NaCl.
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The Periodic Table of the Elements
Most Probable Oxidation State
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0
2
3
_4
- 3
- 2
- 1
H
He
Li
Be
B
C
F
O
N
Ne
3
4
Na
Mg
Al
Si
Cl
S
P
2
1
5
Ar
K
Sc
Ca
Ga
Ti
Ge
Br
Se
As
Zn
Cu
V
Kr
Cr
Mn
Fe
Co
Ni
Rb
Sr
Zr
I
Ag
Nb
Xe
Mo
Tc
Ru
Rh
Pd
Y
In
Sn
Te
Sb
Cd
Ba
Hg
Au
Rn
W
Re
Os
Ir
Pt
Cs
La
Tl
Hf
Pb
At
Po
Bi
Ta
Fr
Ra
Ac
Rf
Du
Sg
Bo
Ha
Me
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
3
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
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Fig. 2.20
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Dont use these when naming ionic compounds--they
re ONLY for covalent compounds!!
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Chemical Formulas
Empirical Formula - Shows the relative number of
atoms of each element in the compound.
It is the simplest formula, and is
derived from masses of the elements. Molecular
Formula - Shows the actual number of atoms
of each element in the molecule of the
compound. Structural Formula - Shows the actual
number of atoms, and the bonds between
them that is, the arrangement of
atoms in the molecule.
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Figure 2.23 Molecular model of nitric acid.
What is the formula for nitric acid?
HNO3
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Conceptual Problem 2.26 model of water, KCI,
methanol, ammonia.
water
ammonia
ethanol
potassium chloride
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Conceptual problem 2.63 Ball and stick model of
hydrogen, oxygen, and carbon.
C3H6O2
PCl5
NO2
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Problem 2.64 Models of sulfuric acid, benzene,
and 2-propane.
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Figure 2.28 Representation of the reaction of
methane with oxygen.
Write a balanced chemical reaction for this
combustion reaction.
CH4(g) 2 O2 (g)? 2 H2 O(l) CO2(g)
Write this reaction in words
Methane gas plus 2 oxygens make 2 waters and one
carbon dioxide
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Figure 2.26 The burning of propane gas. Photo
courtesy of American Color.
Write a balanced equation for this
combustion reaction. The products are carbon
dioxide and water. First write the reaction.
C3H8 O2 ? H2O CO2
Then balance it.
C3H8 5 O2 ? 4 H2 O 3 CO2
Then add physical states.
C3H8 (g) 5 O2 (g) ? 4 H2 O (l) 3 CO2 (g)
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Figure 3.3 Reaction of zinc and iodine causing
iodine to vaporize. Photo courtesy of James
Scherer.
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Chemical Equations
Qualitative Information
Reactants
Products
States of Matter (s) solid (l)
liquid (g) gaseous (aq) aqueous
2 H2 (g) O2 (g) 2 H2O (g)
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Balanced Equations

• mass balance (atom balance)- same number of each
  element (1) start with simplest element (2)
  progress to other elements (3) make all whole
  numbers (4) re-check atom balance
• charge balance (no spectator ions)

1 CH4 (g) O2 (g) 1 CO2 (g) H2O (g)
1 CH4 (g) O2 (g) 1 CO2 (g) 2 H2O (g)
1 CH4 (g) 2 O2 (g) 1 CO2 (g) 2 H2O (g)
Ca2 (aq) 2 OH- (aq) Ca(OH)2 (s)
Na
Na
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Balancing Chemical Equations - I
Problem The hydrocarbon hexane is a component of
Gasoline that burns in an
automobile engine to produce carbon dioxide and
water as well as energy. Write the
balanced chemical equation for
the combustion of hexane (C6H14). Plan Write
the skeleton equation from the words into
chemical compounds with blanks
before each compound. begin the
balance with the most complex compound first, and
save oxygen until last! Solution
C6H14 (l) O2 (g)
CO2 (g) H2O(g) Energy
Begin with one Hexane molecule which says that we
will get 6 CO2s!
1
6
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Balancing Chemical Equations - II
The H atoms in the hexane will end up as H2O, and
we have 14 H atoms, and since each water
molecule has two H atoms, we will get a total of
7 water molecules.
1
6
7
Since oxygen atoms only come as diatomic
molecules (two O atoms, O2),we must have even
numbers of oxygen atoms on the product side. We
do not since we have 7 water molecules!
Therefore multiply the hexane by 2, giving a
total of 12 CO2 molecules, and 14 H2O molecules.
This now gives 12 O2 from the carbon dioxide, and
14 O atoms from the water, which will be another
7 O2 molecules for a total of 19 O2 !
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Predicting the Ion an Element Will Form in
Chemical Reactions
Problem What monoatomic ions will each of the
elements form? (a) Barium(z56) (b) Sulfur(z16)
(c) Titanium(z 22) (d) Fluorine(z9) Plan We
use the z value to find the element in the
periodic table and which is the nearest noble
gas. Elements that lie after a noble gas will
loose electrons, and those before a noble gas
will gain electrons.
Solution (a) Ba2, Barium is an alkaline
earth element, Group 2A, and is expected to
loose two electrons to attain the same number of
electrons as the noble gas Xenon!
(b) S -2, Sulfur is in the Oxygen family, Group
6A, and is expected to gain two electrons to
attain the same number of electrons as the noble
gas Argon!
(c) Ti4, Titanium is in Group 4B, and is
expected to loose 4 electrons to attain
the same number of electrons as the noble gas
Argon!
(d) F -, Fluorine is in a halogen, Group 7A, and
is expected to gain one electron, to attain
the same number of electrons as the noble gas
Neon!