Colorful Chemistry!!!

Rainbows! What color light comes from the sun? WHITE! When it rains (or when you turn on a sprinkler) the droplets of water split the white sunlight into all of the colors of the rainbow Water acts like a prism: Another prism can also recombine the colors back into white light

Colors of the rainbow Remember? ROYGBIV (pronounced roy-gee-biv) Red Orange Yellow Green Blue Indigo Violet

Primary Colors of Pigments In art, when using crayons, paints, and other mediums, we think of the primary colors as: ◦ Red ◦ Blue ◦ And yellow This is misleading “Pigments” are what we really use to color everything around us, from crayons to printer ink The primary colors pigments are: ◦ Magenta ◦ Cyan ◦ And yellow! Ever looked at the bottom of a printer cartridge?

Primary Colors of Light Light acts opposite of pigmnets The primary colors of light are: ◦ Red ◦ Blue ◦ And green! Together, they make white light!

Secondary Colors Secondary colors of pigments: ◦ Blue ◦ Red ◦ And green. Just like the primary colors, light has opposite secondary colors. They are: ◦ Yellow ◦ Cyan ◦ And magenta.

What is light? Light is made of particles called photons. These photons are like packets of energy and they travel through space in a wave In light, a wave looks something like this: Wavelength

Light as a wave The wavelength of light represents how much energy the light wave has The shorter the wavelength, the more energy The longer the wavelength, the less energy We see the different colors of light because each different color has a different wavelength Which color has the most energy? Which color has the least energy?

But… That is just the light we can see. The electromagnetic spectrum is HUGE!!!

Let’s put it in perspective:

Parts of a wave Peak Trough Wavelength Amplitude

Speed of light Wavelength of light waves cause the different colors and types of light, but all light travels the same speed Speed of light = 3.0 x 10 8 meters per second Universal speed limit, nothing can go faster than light!

Speed of light That is almost the distance from here to the moon… EVERY SECOND!!! (actual travel time to the moon is 1.2 seconds That’s 700 million miles per hour! Now to put our solar system in perspective… it takes 8 and ½ minutes for light from the sun to reach earth

Frequency Frequency is how many waves (peak to peak) pass a point in a given amount of time (usually each second) ◦ Since the speed of light is always the same, the wavelength of the wave will change the frequency ◦ As wavelength decreases, frequency increases

Light and atoms Remember how electrons were responsible for electricity? Well they are also responsible for light. When an atom is energized by an energy source, electrons can jump up energy levels (aka orbitals)

Light and atoms continued… When an excited electron finally decides to jump back down to his normal position, he lets off a photon:

Jumping electrons Different energy level jumps from different elements will cause different color light to be emitted. Big jump = big energy! Little jump = little energy

Colorful world Most chemicals do not have electrons that jump up and down when light hits them Most of the time, when light hits a surface, it either bounces off or is absorbed You can see because cells in your eyes are adapted to detecting different the wavelengths of light, as long as the light makes it to your eye

Colorful world continued… When light hits a white lab coat, it absorbs very little light and bounces most of it back to our eyes. All of the colors bouncing back makes the coat look white. When light hits a black lab bench, it absorbs almost all of the light and not much of the light bounces off of it. Since not much light makes it back to our eyes, it looks black. So that means a blue shirt would absorb red and green light and bounce back blue light

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