8.1 Ionic Bonding
Ck12 Science
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Printed: November 25, 2014
AUTHOR
Ck12 Science
www.ck12.org
C HAPTER
Chapter 1. 8.1 Ionic Bonding
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8.1 Ionic Bonding
• Define ionic compound.
• Define ionic bond.
• Use electron dot diagrams to illustrate electron transfer and ionic bond formation.
Does the sea really have salt in it?
We can get common table salt from several sources. It can be mined in the solid form in salt mines or found as a
solid in deposits. We can also get salt from the ocean, but it really does not exist as salt when in solution. The
sodium ions and chloride ions are dissolved, but not combined into a structure until all the water is removed.
Most of the rocks and minerals that make up the Earth’s crust are composed of positive and negative ions held
together by ionic bonding. An ionic compound is an electrically neutral compound consisting of positive and
negative ions. You are very familiar with some ionic compounds such as sodium chloride (NaCl). A sodium
chloride crystal consists of equal numbers of positive sodium ions (Na+ ) and negative chloride ions (Cl− ).
Ionic Bonds
Oppositely charged particles attract each other. This attractive force is often referred to as an electrostatic force. An
ionic bond is the electrostatic force that holds ions together in an ionic compound. The strength of the ionic bond
is directly dependent upon the quantity of the charges and inversely dependent on the distance between the charged
particles. A cation with a 2+ charge will make a stronger ionic bond than a cation with a 1+ charge. A larger ion
makes a weaker ionic bond because of the greater distance between its electrons and the nucleus of the oppositely
charged ion.
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Electron Dot Diagrams
We will use sodium chloride as an example to demonstrate the nature of the ionic bond and how it forms. As you
know, sodium is a metal and loses its one valence electron to become a cation. Chlorine is a nonmetal and gains
one electron in becoming an anion. Both achieve a noble-gas electron configuration. However, electrons cannot be
simply “lost” to nowhere in particular. A more accurate way to describe what is happening is that a single electron
is transferred from the sodium atom to the chlorine atom as shown below.
The ionic bond is the attraction of the Na+ ion for the Cl− ion. It is conventional to show the cation without dots
around the symbol to emphasize that the original energy level that contained the valence electron is now empty. The
anion is now shown with a complete octet of electrons.
For a compound such as magnesium chloride, it is not quite as simple. Because magnesium has two valence
electrons, it needs to lose both to achieve the noble-gas configuration. Therefore, two chlorine atoms will be
needed.
The final formula for magnesium chloride is MgCl2 .
Summary
• An ionic compound contains positive and negative ions.
• An ionic bond is electrostatic in nature.
• Electron dot diagrams can be used to illustrate electron movements and ion formation.
Practice
Questions
Use the link below to answer the following questions:
http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Ionic-Bonding-565.html
1. What do cations and anions form?
2. What influences attraction for electrons?
3. What metals generally form ionic bonds?
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Chapter 1. 8.1 Ionic Bonding
Review
Questions
1. What is an ionic compound?
2. What is an ionic bond?
3. Which cation (Na+ or Ca2+ ) would form a stronger ionic bond with Cl−
• electrostatic force: Attraction of oppositely charged particles toward one another.
• ionic bond: The electrostatic force that holds ions together in an ionic compound.
• ionic compound: An electrically neutral compound consisting of positive and negative ions.
References
1. Leon Brooks. http://commons.wikimedia.org/wiki/File:Wanneroo_Beach-dsc20050514_155534_24.jpg .
2. CK-12 Foundation - Joy Sheng. .
3. CK-12 Foundation - Joy Sheng. .
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