QUIZE 2Define 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 increasesB. atomic radius decreases and electronegativity increasesC. atomic radius increases and electronegativity decreasesD. atomic radius decreases and electronegativity decreases

Dr.Riham Hazzaa 1

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.

C(s)+O2(g)CO2(g)

   H2O  

4 Fe(s)+3 O2(g)2 Fe2O3(s) +3 H2O 

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2. PeroxidesThe O2

2- 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.

• The Lewis structure of hydrogen peroxide contains an O-O single bond

BaO2(s) +2 H+(aq)Ba2+(aq)+H2O2(aq)

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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. By passing an electric current through water. 2 H2O2(aq)O2(g)+2 H2O(l)

 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.

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)

 MnO2   

2 KClO3(s)2 KCl(s)+3 O2(g)

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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.

• This trend is mirrored by an increase in the reducing strength of the corresponding halides. I- > Br- > Cl- > F-

• reducing strength

F2 > Cl2 > Br2 > I2

oxidizing 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.

• Bromine was prepared by reacting bromide ions with a solution of Cl2 dissolved in water.

2 I-(aq)+Br2(aq)I2(aq)+2 Br-(aq)

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.

• Hydrochloric acid is prepared by reacting table salt with sulfuric acid, and hydrofluoric acid is prepared from fluorite and sulfuric acid.

•

H2(g)+Cl2(g)2 HCl(g)  

2 NaCl(s)+H2SO4(aq)2 HCl(aq)+Na2SO4(aq)

CaF2(s)+H2SO4(aq)2 HF(aq)+CaSO4(aq)

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Common Oxidation Numbers for the Halogens

OxidationNumber 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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