Sticky Molecules Activity A

​Sticky Molecules Activity A

Go to launchpad.classlink.com/conejousd and launch Gizmos using the ExploreLearning button. Once in Gizmos, open the Sticky Molecules Gizmo​

Open Ended

Gizmo Warm-up

In the Sticky Molecules Gizmo, you will discover what causes this “stickiness.” You will investigate a variety of phenomena that result from the attraction of molecules to one another.

To begin, drag a dropper bottle of Water and a Petri dish (labeled Polarity) to the simulation area. Drag the dropper over the dish to add water.  Examine the molecules. 

What do you notice about the water molecules?

​Different areas of the water molecules are electrically charged. The red portions of the molecules are negatively charged, while the blue regions are positive. Purple is neutral.

Open Ended

Note the yellow lines which show attractions between the molecules. Why do you think these attractions occur? 

​Activity A: Polarity

Get the Gizmo ready: 

• Check that the Petri dish contains water.

Open Ended

Introduction: All molecules are neutral overall. However, the charges within molecules are not always arranged in the same way. In a polar molecule the positive and negative charges are separated into distinct regions. In a nonpolar molecule the charges are evenly dispersed.

Classify: Based on what you observe, are water molecules polar or nonpolar? Why do you think so?

​

The presence of charged regions indicates a polar molecule. However, these charged regions do not represent full charges as found in compounds such as sodium chloride. Instead they are partial positive (δ+) and partial negative (δ–) charges, which are much weaker than full charges.

Open Ended

Hypothesize: Note the yellow lines that form between molecules, which represent hydrogen bonds. A hydrogen bond (H-bond) is an example of an intermolecular force (IMF). IMFs occur between all molecules, but hydrogen bonds are the strongest.

What do you think causes these H-bonds to form? (Hint: Look at the charged regions.)

Open Ended

Why do you think the H-bonds only last a short time before breaking and reforming?

Multiple Choice

Explore: Replace water with hexane (an ingredient in paint thinner). Examine the molecules. Do you see any charged regions?

• Yes

• No

Multiple Choice

Do any H-bonds form in hexane?

• Yes

• No

Multiple Choice

Is hexane polar or nonpolar?

• polar

• nonpolar

Multiple Choice

Observe and classify the other two liquids. Which one is polar?

• Glycerin

• Mineral Oil

Multiple Choice

Summarize: Molecules that are attracted to one another can be called “sticky.” Which types of molecules, polar or nonpolar, are the “stickiest”?

• polar

• nonpolar