Before we can address the nature of the atom, we must first discuss some __similar__ properties of light...

__Light__ - also called "Electromagnetic Radiation."

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**Electromagnetic Radiation (EMR)**

** Energy**, in the form of "light," travels through space by

__electromagnetic radiation__.

There are only seven types of EMR which together make up the electromagnetic spectrum.

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**The Electromagnetic Spectrum**

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**Electromagnetic Spectrum - Notes**

1. Light (EMR) * only* differs in its energy, frequency, and wavelength.

2. __Visible light__ only makes up a "sliver" of the electromagnetic spectrum.

3. Soon we will see the mathematical relationship between energy (E), wavelength (λ), and frequency (ν).

4. To remember the __complimentary colors__ for visible light, use (and sound out):

**" VY BO GR "**

➞ If __violet__ light is absorbed, objects appear __yellow__.

➞ if __yellow__ light is absorbed, objects appear __violet__.

➞ etc.. for the other pairs...

➞ we'll drop / ignore "I" (indigo)

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**Wavelength and Frequency of Light**

Check out the two __waves__ in the drawing below. But first, a few definitions:

**Wavelength (λ)** - distance between two consecutive peaks (or troughs) in a wave.

**Frequency (ν)** - the number of cycles (waves) per second traveling past a fixed point.

As you can see above, the longer the wavelength, the lower the frequency, and vice-versa.

To put this visually we have the mathematical relationship between frequency and wavelength...

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**Wavelength and Frequency Relationship**

In fact, multiplying the wavelength (λ) times the frequency (ν) will always equal the same value.

And this value is the * speed of light (c)*.

c = 2.9979 x 10^{8} meters/second.

Often you'll see **c = 3.0 x 10 ^{8} m/s**...

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**Frequency Wavelength Formula**

Let's make sense of this by doing a sample problem using * λν = c* below...

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**Frequency Wavelength Calculation**

*ex:* Calculate the frequency of red light having a wavelength of 6.50 x 10

^{2}nm.

_________

**answer:**➞ first, we'll need to convert our wavelength from nanometers to meters.

➞ so, "*start with what we're given and put it over 1*"...

Okay good. Now we can actually * DO* the problem:

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__Next up__, in **SECTION 7 - Quantum-Mechanical View of the Atom, and Periodicity...**

We'll see a video and discuss the wave-particle duality of light, the de Broglie wavelength, and the photoelectric effect... 👍