Session Digital: Volumes 💨

Representing 3D molecules in 2D

What color is used to show a carbon atom?

What color is used to show a nitrogen atom?

What color is used to show an oxygen atom?

What color is used to show a hydrogen?

What color is used to show a sulphur?

What color is used to show a chlorine?

Draw the full structural formula of these molecules. Click and drag to rotate them so you can see better.

• ethane
• isopropanol
• cadaverine
• benzene
• aspirin
• sexithiophene
• cubane
• caffeine

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See the [Help] tab for the answers as well as what these molecules do.

Note that these are possible answers --- you may have rotated your structural formula and have one that looks different.

The software used in the intro video is called SAMSON (Software for Adaptive Modeling and Simulation Of Nanosystems), and is a kind of molecular modeling tool. You will learn to operate these in the future.

Molecular Formula

Deduce the molecular formula of these molecules. If you have not completed the previous puzzle I suggest you to do them first.

• ethane
• isopropanol
• cadaverine
• benzene
• aspirin
• sexithiophene
• cubane
• caffeine

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Be careful of the ordering!

Ethane

C₂H₆

Isopropanol

C₃H₈O

cadaverine

C₄H₁₄N₂

benzene

C₆H₆

aspirin

C₉H₈O₄

sexithiophene

C₂₄H₁₄S₆

cubane

C₈H₈

caffeine

C₈H₁₀N₄O₂

Is there a way to simplify the full structural formula without losing information? 🧐

Yes there is --- there is actually two ways to do that! They are called:

1. Skeletal structural formula (preferred), and
2. Condensed structural formula

Look for them in future episodes.

Unit Conversions: Volumes

Convert 100 nm³ to nm³.

Use the sliders below to create four questions of increasing difficulty.

• Å
• nm
• μm

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Convert 100 dm³ to dm³.

Use the sliders below to create four questions of increasing difficulty.

• cm
• dm
• m

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Use your graphical calculator for the next parts.

If we approximate a water molecule as a sphere, its diameter would be 2.75 Å. What is its volume?

How many water molecules can fit into 1 dm³?

Once again, with feelings: if you get some wrong, it is probably because you skipped steps.

Essential Habit 1

Do this on paper.

Essential Habit 2

If necessary, break each conversion into steps. Use a conversion factor to change to intermediate units. You trade speed for accuracy, and it is a good trade. There is no prize for the first to be wrong.

Essential Habit 3

Write out all units and factor-of-ten explicitly. Cross out units. What remains should be "nm". If it is not, something is wrong with your set up.

It is quite inconvenient to refer to such large number of objects. Nowhere else in life do we ever need 10²⁰⁺. I wonder if there is a way to simplify that? 🧐

Homework

A new Anki deck for molecular formula had been added to the Google Drive. Install it, and keep doing your Anki decks.

Read section 3.1 (The Periodic Table) in your textbook, complete the exercise, and mark your answers. Complete by (Sun) 21:00. This should take no more than 20 minutes.

This is an intentionally light week. Use this time to catch up on what you have