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Ionic Bonding Lab
How Do Ions Form?
You and a friend walk past a market that sells apples for 40 cents each and pears for 50 cents each.
You have 45 cents and want an apple. Your friend also has 45 cents but wants a pear. If you give
your friend a nickel, she will have 50 cents and can buy a pear. You will have 40 cents left to buy an
apple. Transferring the nickel gets both of you what you want. In a simple way, your actions model
what can happen between atoms.
What is an Ion?
An ion is an atom or group of atoms that has an electric charge. When a neutral atom loses a valence
electron (-), it loses a negative charge. It becomes a positive ion (+). When a neutral atom gains an
electron (-), it gains a negative charge. It becomes a negative ion (-). These negative and positive
ions are now attracted to each other, and form a bond. This is called an ionic bond. Even though
they are attracted, the positive ion remains positive and the negative ion remains negative.
Therefore, positive and negative ions will continue to be attracted to each other +-+-+-+- in all three
dimensions, and form large bonds, limited only by the number of ions available.
To help illustrate this concept, let’s draw some atoms before and after they bond.
Before Bonding
Draw an electron dot diagram of a Sodium (Na)
atom. Highlight or color the valence electron.
Next, draw an electron dot diagram of a Fluorine
(F) atom. Highlight or color the valence
electrons.
Discuss: What do you notice about the valence electrons in each atom?
Predict: What do you think will happen as a result of these valence electrons?
After Bonding
Draw an electron dot diagram of a Sodium (Na+)
ion.
Draw an electron dot diagram of a Fluorine (F-)
ion.
Explain: What happened? ____________________________________________________________________________________
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This ionic bond forms a compound called Sodium Fluoride NaF.
Now let’s take a look at a more common ionic bond, sodium chloride (table salt). Since you already
drew a Sodium atom, in the space below, draw an electron dot diagram for a chlorine atom.
Chlorine (Cl)
Predict: What will happen between these two
atoms?
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Working with your lab partners, put a small scoop of table salt onto the microscope slide. Adjust the
lens until you get a good view of the salt crystals. In the space below, draw a picture of what you
see. Try to draw in three dimensions.
When you are finished, answer the following questions and discuss with your group:
What do you notice about the shape of the salt crystals? __________________________________________________
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Do you think these shapes are natural or man made? _____________________________________________________
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What materials occurring naturally on earth also look like this? _________________________________________
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What do all these materials have in common? (Hint: Are they solid, liquid or gas?)
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What parts of our bodies may also be the result of ionic bonding? (Hint: What parts are also solid?)
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What would happen if you were made entirely of ionically bonded materials?
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Does this mean that there are other forms of bonding, other than ionic? _____________
(This is what we will learn next.)
In the space below, draw an electron dot diagram of the ions after they bonded. Make sure you
account for the electrons that have transferred.
Sodium (Na+)
Chloride (Cl-)
Do you have any questions about ions, or ionic bonding?
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