Question

activity b: building molecules
get the gizmo ready: click reset. turn off show lewis diagram. select oxygen.
question: how do atoms share more than one pair of electrons?

1. observe: 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? ____________

1. form a bond: drag electrons back and forth until the molecule of oxygen (o₂) is stable. click check to confirm your molecule is stable. take a snapshot and paste the image into your document (dont forget to label it “o₂”).

turn on highlight shared electrons. how many pairs of shared electrons are there in a stable molecule of oxygen? ____________

1. draw a diagram: draw a lewis diagram of the oxygen molecule in the space below at left. to check your work, turn on show lewis diagram. draw the correct diagram on the right.

practice diagram: o o actual: o o

1. practice: create covalent bonds and stable molecules for the remaining substances. take a snapshot of each completed molecule and add it to your document. draw lewis diagrams for each one. (as above, draw the diagram on your own before checking your work.)

nitrogen n n ammonia h n h
chlorine cl cl
methane h c h h
water h o h
carbon dioxide o c o formaldehyde h c h h
(activity b continued on next page)

Explanation:

Step1: Determine oxygen's valence - electrons

Oxygen is in group 16 of the periodic table. Each oxygen atom has 6 valence electrons.

Step2: Calculate electrons needed for stability

An atom is stable with 8 valence electrons. Since oxygen has 6 valence electrons, it needs 8 - 6=2 more electrons to be stable.

Step3: Analyze shared - electron pairs in O₂

In a stable oxygen molecule (O₂), each oxygen atom shares 2 pairs of electrons with the other oxygen atom to achieve an octet.

Answer:

A. 6
B. 2

1. 2