Post on 16-Dec-2015
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Ionic Bonds and Ionic CompoundsForming Compounds from Ions
+Objectives
When you complete this presentation, you will be able to …explain the electrical charge of an
ionic compound.describe three properties of ionic
compounds.
+Formation of Ionic Compounds:Introduction
Ionic compounds are composed of a mixture ofcations (ions with positive charges)anions (ions with negative charges)
Cations are usually metal ions.
Anions are usually nonmetal ions.
The compounds are usually electrically neutral.
+Formation of Ionic Compounds:Ionic Bonds
Cations and anions have opposite charges.
They are attracted to each other by electrostatic forces.
These forces are called ionic bonds.
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Bonds are formed by an exchange of electrons.
For example:
Na + Cl ➞ Na+ + Cl–
Formation of Ionic Compounds:Ionic Bonds
• •
• ••••• ••••
• •
• •
The NaCl formed is a neutral compound.
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Bonds are formed by an exchange of electrons.
For example:
Formation of Ionic Compounds:Ionic Bonds
Ca + Cl ➞ Ca2+ + Cl–+ Cl + Cl–• •
• •••••
• • •
• •••• ••••
• •
• •••••
• •
• •
The CaCl2 formed is a neutral compound.
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Ionic compounds are composed of equal numbers of positive charges and negative charges.NaClCaCl2
Formation of Ionic Compounds:Formula Units
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A chemical formula is meant to represent the kinds and numbers of atoms in the simplest representative unit of the compound. For example: C6H12O6 indicates that there are
six carbon atoms, twelve hydrogen atoms, and six oxygen atoms in the compound glucose.
For example: NaCl indicates that there is one sodium atom (ion) for each chloride atom (ion) in the compound of sodium chloride.
Formation of Ionic Compounds:Formula Units
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Ionic compounds (like sodium chloride) exist as large collections of ions (+ and –) and not as a collection of discrete molecules (like glucose).
This means that we use the lowest whole number ratio for the chemical formulas of ionic compounds.
These are called formula units.
Formation of Ionic Compounds:Formula Units
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Most ionic compounds are crystalline solids at room temperature. For example: sodium chloride (NaCl) For example: aragonite (CaCO3)
For example: rutile (TiO2)
Ionic compounds generally have high melting points.
Properties of Ionic Compounds
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Each ion in an ionic compound has a certain number of oppositely charged ions surrounding it.
That number is called the coordination number.
Properties of Ionic Compounds
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For example: In sodium chloride (NaCl), each Na+ is surrounded by six Cl– and each Cl– is surrounded by six Na+. The coordination number of Na+ is six. The coordination number of Cl– is six.
Properties of Ionic Compounds
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For example: In cesium bromide (CsBr), each Cs+ is surrounded by eight Br– and each Br– is surrounded by eight Cs+. The coordination number of Cs+ is eight. The coordination number of Br– is eight.
Properties of Ionic Compounds
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For example: In titanium dioxide (TiO2), each Ti4+ is surrounded by six O2– and each O2– is surrounded by three Ti4+. The coordination number of Ti4+ is six. The coordination number of O2– is three.
Properties of Ionic Compounds
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Ionic compounds are generally conductive when melted or dissolved in water. When an ionic compound is melted
the orderly arrangement of ions is destroyed
the ions are free to migrate as they please an electric voltage will cause the cations to
migrate to one pole and the anions to migrate to the other pole.
Properties of Ionic Compounds
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Something similar happens when an ionic compound dissolves in water.
Properties of Ionic Compounds
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Ionic compounds are composed of a mixture of cations (ions with positive charges) and anions (ions with negative charges)
Cations are usually metal ions and anions are usually nonmetal ions.
Ionic compounds are usually electrically neutral.
Summary
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Cations and anions are attracted to each other by electrostatic forces called ionic bonds.
Bonds are formed by an exchange of electrons.
Ionic compounds are composed of equal numbers of positive charges and negative charges.
Summary
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Cations and anions are attracted to each other by electrostatic forces called ionic bonds.
The chemical formulas for ionic compounds use the lowest whole number ratio for the chemical formulas of ionic compounds which are called formula units.
Summary
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Cations and anions are attracted to each other by electrostatic forces called ionic bonds.
Most ionic compounds are crystalline solids at room temperature.
Ionic compounds generally have high melting points.
Summary
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Each ion in an ionic compound has a certain number of oppositely charged ions surrounding it which is called the coordination number.
Ionic compounds are generally conductive when melted or dissolved in water.
Summary