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?
2.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?
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?
2. Click Pause ( ). Drag an electron from the left atom to the right atom. Click Play. What happens?
3. Click Pause, drag an electron from the right atom to the left, and then click Play. What happens now
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 theoctet 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?
Form a bond: Drag the electrons so that they move around both hydrogen atoms. Click Playto observe them in orbit, and then click Check. You have created a .
Congratulations, you have completed a of hydrogen! Because the molecule has two atoms, it is a . Click the () icon to take a snapshot of your completed molecule. Right-click the image, and click Copy Image. Paste the image into a blank document and label the image “H2.”
Draw a diagram: Covalent bonds are shown in . In a Lewis diagram, dots represent unshared valence electrons and dashes represent pairs of shared electrons.
Turn on . What is the Lewis diagram for hydrogen, H2?