Chemical Formulas
Chemical Bonding
Stoichiometry
COURSE NAME: CHEMISTRY 101
COURSE CODE: 402101-4
Chapter
6
1
2
3
Chemical Formulas
4
5
5
6
Chemical Bonding
Ionic bond
Ionic bond is formed when metal (electropositive element) lose
electrons forming positive ion and nonmetal (electronegative
element) gain these electrons forming negative ion.The ionic bond
results from the electrostatic attraction between the positive
(cation) and negative ion (anion).
An example of an ionic compound is NaCl where Na is of low
ionization potential and Cl is of high electron affinity. Thus, an
electron is taken up by Cl from Na to become Cl- and Na then
becomes Na+. Electrostatic attraction then occurs between the two
ions to form ionic bond.
Na + Cl →
Na+ Cl-
7
8
9
Covalent Bond (electron –pair bond)
The bond formed when two atoms mutually share their
electrons. In the other words, it is the bond formed by sharing
a pair of electrons by two atoms e.g.
H· + H· → H··H or (H-H)
9
10
When the two atoms are of similar electronegativity the
covalent bond is nonpolar. On the other hand, when the
two atoms are of different electronegativity, the bond is
polar covalent bond e.g. H-Cl ; chlorine atom is more
electronegativily and attracts the bond electrons more
strongly than hydrogen.
Thus, the structure is written as
Hδ+ ─ Clδ-
Chlorine carries partial negative charge but the
hydrogen carries partial positive charge.
10
11
11
Coordination bond
This bond formed when a pair of electrons from one atom is
shared between two atoms.
Also it can be defined as the bond formed by the interaction
of two atomic orbitals one is doubly occupied and the other is
empty; the first is called donor and the second is called
acceptor.
H
H
H
F
N
B
F
F
H
Donor
Acceptor
H
F
N
H
B
F
F
Compound
We write simply the product as H3N+BF312
13
Hydrogen bond
The attractive force that binds a hydrogen atom which is
covalently attached with a strongly electronegative atom of a
molecule with another electronegative atom of some other
molecule. Thus the existence of hydrogen bond between A-H
and B-H molecules can be shown as:
Aδ-Hδ+ ….. Bδ-Hδ+
Where A and B are strongly electronegative atoms
13
14
Stoichiometry
Definition: predicting the amounts of reactants and/or
products that will be involved in a reaction
Must use a balanced reaction Why?
Because matter can neither be created nor destroyed.
If you try to use a reaction like:
H2 + O2H2O
14
You will have one oxygen atom that does not get used. You
have to take that into consideration otherwise the reaction is
not an accurate description of what is happening
Since you are only using ½ of the O2 molecule:
H2 + ½ O2H2O
This is the same as:
2 H2 + O2 2 H2O
Coefficients tell you the relative amounts of products
and reactants
Coefficients are in units of moles
15
Example: N2 + 3 H2 2 NH3
Recall that the coefficient on N2 is 1 but is not explicitly
written in the reaction Coefficients:
N2 = 1
H2 = 3
NH3 = 2
Using the coefficients we can write mole ratios
16
17
Definition: mole ratio gives the relative amounts of
reactants and products
17
MOLE to MOLE Stoichiometry
18
MASS to MASS Stoichiometry
19
You can use this version of the mole map to solve stoichiometry problems.
20
1. Determine the number of moles
of aluminum in 0.2154 kg of Al.
A)
1.297 x 1023 mol
B)
5.811 x 103 mol
C)
7.984 mol
D)
0.1253 mol
E)
7.984 x 10-3 mol
3. What is the coefficient for CO2
when the following chemical
equation is properly balanced
using the smallest set of whole
numbers?
C4H10 + O2 ----> CO2 + H2O
A)
1
B)
4
2. How many phosphorus atoms are
C)
6
there in 2.57 g of P?
D)
8
A)
4.79 x 1025
E)
12
B)
1.55 x 1024
C)
5.00 x 1022
D)
8.30 x 10-2
E)
2.57
21
4. What mass of copper(II)
nitrate would be produced
from the complete reaction
of 45.6 g of copper,
according to the chemical
reaction shown below?
Cu + 2 AgNO3 ----> Cu(NO3)2
+ 2 Ag
A)
0.72 g
B)
21.1 g
C)
98.7 g
D)
135 g
E)
187 g
5. Calculate the number of
moles of H2O formed when
0.200 mole of Ba(OH)2 is
treated with 0.500 mol of
HClO3 according to the
chemical reaction shown
below.
Ba(OH)2 + 2 HClO3 ---->
Ba(ClO3)2 + 2 H2O
A)
1.00 mol
B)
0.600 mol
C)
0.500 mol
D)
0.400 mol
E)
0.200 mol
22
6. The limiting reagent is the
substance:
A)
present
in
greatest
quantity
B)
limits the number of
reagents present
C)
determined
by
the
amount of reactants present
D)
that
determines
the
maximum amount of possible
product
7. One mole of H2
A)
contains 6.0 x 1023
H atoms.
B)
contains 6.0 x 1023
H2 molecules.
C)
contains 1 g of H2.
D)
is equivalent to 6.02
x 1023 g of H2.
E)
None of the
above.
23
8. How many oxygen atoms are 10. Determine the mass percent
present in 5.2 g of O2?
of iron in Fe4[Fe(CN)6] 3.
A)
5.4 x 10-25 atoms
A)
45% Fe
B)
9.8 x 1022 atoms
B)
26% Fe
C)
2.0 x 1023 atoms
C)
33% Fe
D)
3.1 x 1024 atoms
D)
58% Fe
E)
6.3 x 1024 atoms
E)
None
of
the
above.
9. What is the mass of 5.45 x 10-3 11. When it is correctly
mol of glucose, C6 H12O6?
balanced,
the
correct
A)
0.158 g
coefficients for the equation
B)
982 g
below are PCl3 + H2O ---->
C)
3.31 x 104 g
H3PO3 + HCl
D)
0.982 g
A)
1, 3, 1, 1
E)
None of the above.
B)
1, 3, 1, 3
C)
1, 1, 1, 3
D)
2, 3, 2, 3
24