Question

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.)

1. 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?

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.

1. the outermost electrons in each atom are called valence electrons. how many valence electrons does each fluorine atom have?
2. click pause (⏸). drag a valence electron from the left atom to the right atom. click play. what happens?
3. click pause, drag a valence electron from the right atom to the left, and then click play. what happens now?

Explanation:

Step1: Analyze Flora and Frank's situation

Flora has 7 markers and is missing red, Frank has 7 markers and is missing blue. They can trade the markers they are missing. So Flora gives Frank her blue - marker and Frank gives Flora his red - marker.

Step2: Analyze Otto and Olivia's situation

Otto has 6 markers and is missing purple and green, Olivia has 6 markers and is missing black and brown. They can trade the markers they are missing. Otto gives Olivia his black and brown markers, and Olivia gives Otto her purple and green markers.

Step3: Determine valence electrons of Fluorine

Fluorine is in group 17 of the periodic table. The number of valence electrons of an element in group 17 is 7. So each fluorine atom has 7 valence electrons.

Step4: Analyze electron - transfer in Fluorine atoms (first transfer)

When a valence electron is dragged from the left atom to the right atom, the right atom gains an electron and becomes more negatively charged relative to the left atom.

Step5: Analyze electron - transfer in Fluorine atoms (second transfer)

When a valence electron is dragged from the right atom to the left atom, the left atom gains an electron and the two atoms are now in a more stable state as they are sharing electrons to form a covalent bond.

Answer:

1. Flora and Frank can trade the markers they are missing (Flora gives Frank her blue - marker and Frank gives Flora his red - marker).
2. Otto and Olivia can trade the markers they are missing (Otto gives Olivia his black and brown markers, and Olivia gives Otto her purple and green markers).
3. Each fluorine atom has 7 valence electrons.
4. When a valence electron is dragged from the left atom to the right atom, the right atom becomes more negatively charged relative to the left atom.
5. When a valence electron is dragged from the right atom to the left atom, the two atoms share electrons to form a covalent bond.