QUIZE 2
Define Ionization Energy. Write trends of Ionization Energy
in periodic table, and why?
Write the reaction between lithium Li and nitrogen.
As you move up and to the right on the periodic table:
A. atomic radius increases and electronegativity increases
B. atomic radius decreases and electronegativity increases
C. atomic radius increases and electronegativity decreases
D. atomic radius decreases and electronegativity decreases
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Chemistry of Nonmetals
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The Chemistry of Oxygen ( Group VI)
• The electron configuration of an oxygen atom 1s2
2s2 2p4 suggests that neutral oxygen atoms can
achieve an octet of valence electrons by sharing
two pairs of electrons to form an O=O double
bond, as shown in the figure below.
• According to this Lewis structure, all of the
electrons in the O2 molecule are paired.
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1.Oxygen as an Oxidizing Agent
• Each O2 molecule must gain four electrons to
satisfy the octets of the two oxygen atoms
without sharing electrons
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• Oxygen is the perfect example of an oxidizing
agent because it increases the oxidation state of
almost any substance with which it reacts.
• In the course of its reactions, oxygen is reduced.
The substances it reacts with are therefore
reducing agents.
H2 O
4 Fe(s) +3 O2(g)
2 Fe2O3(s) +3 H2O
C(s)
CO2(g)
+ O2(g)
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2. Peroxides
The O22- ion is called the peroxide ion
The easiest way to prepare a peroxide is to react
sodium or barium metal with oxygen.
2 Na(s) +
O2(g)
Na2O2(s)
Ba(s)
O2(g)
BaO2(s)
+
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• When these peroxides are allowed to react
with a strong acid, hydrogen peroxide (H2O2)
is produced.
BaO2(s) + 2 H+(aq)
Ba2+(aq) + H2O2(aq)
• The Lewis structure of hydrogen peroxide
contains an O-O single bond
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Methods of Preparing O2
1. By decomposing a dilute solution of
hydrogen peroxide with dust or a metal
surface as the catalyst.
2 H2O2(aq)
O2(g) + 2 H2O(l)
2. By passing an electric current through
water.
electrolysis
2 H2O(l)
2 H2(g) + O2(g)
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3. By heating potassium chlorate (KClO3) in the
presence of a catalyst until it decomposes.
MnO2
2 KClO3(s)
2 KCl(s) + 3 O2(g)
4. By reacting hydrogen peroxide with a strong
oxidizing agent, such as the permanganate
ion, MnO4-.
5 H2O2(aq) +2 MnO4-(aq) +6 H+(aq)
2 Mn2+(aq) +5 O2(g) +8 H2O(l)
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The Halogens Group VIIA
• There is a regular increase in many of the
properties of the halogens as we proceed down
the column from fluorine to iodine,
• including the melting point,
• boiling point,
• intensity of the color of the halogen,
• the density of the element.
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• On the other hand, there is a regular decrease
in the ionization energy as we go down this
column.
• As a result, there is a regular decrease in the
oxidizing strength of the halogens from
fluorine to iodine. F > Cl > Br > I
2
2
2
2
oxidizing strength
• This trend is mirrored by an increase in the
reducing strength of the corresponding
halides.
I- > Br- > Cl- > F•
reducing strength
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Methods of Preparing the Halogens from their
Halides
• The halogens can be made by reacting a solution
of the halide ion with any substance that is a
stronger oxidizing agent.
• Iodine can be made by reacting the iodide ion
with either bromine or chlorine.
2 I-(aq) + Br2(aq)
I2(aq) + 2 Br-(aq)
• Bromine was prepared by reacting bromide ions
with a solution of Cl2 dissolved in water.
2 Br-(aq) + Cl2(aq)
Br2(aq) + 2 Cl-(aq)
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• To prepare Cl2, we need a particularly strong
oxidizing agent, such as manganese dioxide
(MnO2).
2 Cl-(aq) + MnO2(aq) + 4 H+(aq)
Cl2(aq) +Mn2+(aq) + 2 H2O(l)
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The Hydrogen Halides (HX)
• Several of the hydrogen halides can be prepared
directly from the elements. Mixtures of H2 and
Cl2, react with explosive violence in the presence
of light to form HCl.
H2(g) + Cl2(g)
2 HCl(g)
• Hydrochloric acid is prepared by reacting table salt
with sulfuric acid, and hydrofluoric acid is
prepared from fluorite and sulfuric acid.
• 2 NaCl(s) + H SO (aq)
2 HCl(aq) + Na SO (aq)
2
CaF2(s)
4
2
+ H2SO4(aq)
2 HF(aq)
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+ CaSO4(aq)
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Common Oxidation Numbers for the Halogens
Oxidation
Number
Examples
-1
CaF2, HCl, NaBr, AgI
0
F2, Cl2, Br2, I2
+1
HClO, ClF
+3
HClO2, ClF3
+5
HClO3, BrF5, BrF6-, IF5
+7
HClO4, BrF6+, IF7
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