Session 1: Colors 🌈

What is Color?

This Toy shows the color for a particular wavelength, measured in nanometers. For those of you with some design experience, the hex color code is shown inside.

Light of 680 nm is ___ (color).

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If you have the colored pens, use it for your notes.

1. Arrange the colors in increasing wavelength
2. Add the colors in the color wheel, placing the complementary colors across each other.

Propose three ways different colors of emission can combine to "create" white light. An example is shown.

If you are checking your color wheel against the internet, note that being radially symmetric, the color wheel could be rotated and still "works".

If you are checking your ordered line against the internet, make sure what you are comparing against is also in wavelength. If you were looking at frequency it would be opposite!

White and white is still white.

What about wavelengths longer than 700 nm, or shorter than 400 nm?

Unit Conversions: Lengths

Convert 100 Å to nanometers.

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

• pm
• Å
• μm
• cm
• dm

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Aim to do each within 20 seconds. You can use calculators to handle the arithmetic.

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Consult your Data Booklet. On which table do you find the atomic radii?

How many Å is the radii of a carbon (C) atom?

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.

You will also see the micrometer μm called a micron μ. This non-SI unit had been abolished for more than 50 years, but people still uses it ¯\_(ツ)_/¯

Before moving on, let's review how objects' sizes can differ by orders of magnitude:

Drawing Atoms

With help from your Data Booklet, draw a helium (He; 2 protons 2 neutrons), Neon (Ne; 10 protons, 10 neutrons), Neon isotope with 11 neutrons, and Argon (Ar; 18 protons, 21 neutrons) atom in your notes. Use the cartoon notation, and the scale bar for reference; try using shading to show the three-dimensional nature of the electron cloud.

Be careful about the difference between the radius and the diameter!

Drawing just one atom can take awhile.

Even if a robot can draw it for us, it's still tedious to count all the purple and gray circles.

What can we do to simplify this?

Homework

Start reading your textbook (Brown & Ford) chapter 2, page 58-66. You will be doing the exercises from these pages in Session 3.