Student Exploration: Covalent Bonds

The outermost electrons in each atom are called valence electrons. How many valence electrons does each fluorine atom have?

They have a total of 7 valence electrons.

Like fluorine and most other elements, oxygen atoms are most stable with a full complement of eight valence electrons. A. How many valence electrons does each oxygen atom have now? B. How many more electrons does each oxygen atom need to be stable?

A. They currently have 6 electrons B. They need two more valence electrons in order to be stable.

Think and discuss: How is the formation of covalent bonds similar to kids sharing markers? How is it different? If possible, discuss your answer with your classmates and teacher.

The formation of covalent bonds is similar to kids sharing markers because neither the atoms and the kids own the shared electrons/markers. Another similarity is that when sharing, it creates stability for both the atoms and the full set of markers. A difference is that in the kids sharing markers, the markers are all different colors but in the covalent bonds, the two atoms are the same molecule. Another difference is that the covalent bonds make up a new molecule while the markers don't.

How many pairs of shared electrons are there in a stable molecule of oxygen?

2 pairs

Click Pause, drag an electron from the right atom to the left, and then click Play. What happens now?

Now both of the fluorine atoms have six electrons on their outermost shell. There's currently two electrons (one pair) orbiting around the oval shell that connects the two fluorine atoms. They are now stable as both fluorine have 8 valence electrons.

Click Pause. Drag an electron from the left atom to the right atom. Click Play. What happens?

The two atoms are now sharing an electron that is orbiting on a shell located between them. The left atom lost an electron（now currently have 6 electrons) on the valence shell.

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?

They are able to combine the markers and so the set is full.

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?

They are able to share the two electrons (covalent bond) to achieve a stable configuration.

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 share the marker so both have a full set. This is similar to a covalent bond because it also involves sharing. (the sharing of electron pairs between atoms.)