Student Exploration: Covalent Bonds
Vocabulary: covalent bond, diatomic molecule, Lewis diagram, molecule, noble gases, nonmetal, octet rule, shell, valence, valence electron
Prior Knowledge Questions (Do these BEFOR
...
Student Exploration: Covalent Bonds
Vocabulary: covalent bond, diatomic molecule, Lewis diagram, molecule, noble gases, nonmetal, octet rule, shell, valence, valence electron
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
There are eight markers in a full set, but Flora and Frank each only have seven markers. Flora is missing the red marker, and Frank is missing the blue marker.
What can they do so that each has a full set of markers? They can single bond together. Otto and Olivia each have six markers. Otto is missing the purple and green markers, and Olivia is missing the black and brown markers. What can they do so that each has a full set? Covalent bond together.
Gizmo Warm-up
Just like the students described above, nonmetal atoms can share electrons. As you will see in the Covalent Bonds Gizmo™, atoms form bonds in this way.
To begin, check that Fluorine is selected from the Select a substance menu. Click Play ( ) to see the electrons orbiting the nucleus of each atom.
The outermost electrons in each atom are called valence electrons. How many valence electrons does each fluorine atom have? Seven.
Click Pause ( ). Drag an electron from the left atom to the right atom. Click Play.
What happens? They begin to bond and the one electron that I moved from the left atom to the right atom encircles both atoms.
Click Pause, drag an electron from the right atom to the left, and then click Play. What happens now? The same happens as the last question and now there are two.
Activity A:
Sharing electrons
Get the Gizmo ready: Click Reset.
Select Hydrogen.
Introduction: The electrons that orbit the nucleus of an atom are arranged into shells. The first shell contains up to two electrons and the second contains up to eight electrons. Most elements are stable when they have eight valence electrons—a rule of thumb known as the octet rule. (Elements with less than five electrons are stable with two valence electrons.)
Question: What happens when atoms share electrons?
Predict: Each hydrogen atom has one valence electron, but it needs two electrons to be stable. How can both hydrogen atoms each achieve a stable configuration? By sharing one electron.
Form a bond: Drag the electrons so that they move around both hydrogen atoms. Click Play
to observe them in orbit, and then click Check. You have created a covalent bond.
Congratulations, you have completed a molecule of hydrogen! Because the molecule has two atoms, it is a diatomic molecule. Click the camera ( ) to take a snapshot of your
completed molecule. Paste the image into a blank document and label the image “H2.”
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