COLORCOLOR

MIHA LEEMIHA LEE

Sun LightSun Light

                                                                         

  

Visible LightVisible Light

Color is the visual perceptual property in humans.

Typical human eye responds to wavelengths to 300~700nm.

Color is the visual perceptual property in humans.

Typical human eye responds to wavelengths to 300~700nm.

Three ways of InteractionThree ways of Interaction

Transparency

=> Transmission of light without scattering Translucency

=> Transmission of light with scattering Opacity

=> Absorption (and/or) Reflection

Transparency

=> Transmission of light without scattering Translucency

=> Transmission of light with scattering Opacity

=> Absorption (and/or) Reflection

Color of materialColor of material

Color is the visible light that is reflected or emitted by a material.

Color as reflected (not absorbed) light Color as emitted light

Color is the visible light that is reflected or emitted by a material.

Color as reflected (not absorbed) light Color as emitted light

Absorption & Emission of Light=> Transition of Electrons

Absorption & Emission of Light=> Transition of Electrons

IndicatorIndicator

Indicators are usually weak acids. HIn H+ + In-

(In an acid solution) (In a base solution)

Le Chatelier’s principle

Indicators are usually weak acids. HIn H+ + In-

(In an acid solution) (In a base solution)

Le Chatelier’s principle

Tomato JuiceTomato Juice

Tomato has lycopene which has a lot of conjugated double bonds.

When lycopene undergoes chemical reactions, the color of tomato juice will be changed.

Tomato has lycopene which has a lot of conjugated double bonds.

When lycopene undergoes chemical reactions, the color of tomato juice will be changed.

Color as Reflected LightColor as Reflected Light

Part of the white light is absorbed and the rest of visible light is reflected.

A substance absorbs some wavelengths of visible light preferentially.

Color of a substance depends on its molecular structure.

Organic dyes and pigments.

Part of the white light is absorbed and the rest of visible light is reflected.

A substance absorbs some wavelengths of visible light preferentially.

Color of a substance depends on its molecular structure.

Organic dyes and pigments.

Color as Emitted lightColor as Emitted light

Usually, the absorbed light change into heat in a substance.

However, some special substances have an ability to give off some specific color of visible light in a certain condition.

Fluorescence Phosphorescence

Usually, the absorbed light change into heat in a substance.

However, some special substances have an ability to give off some specific color of visible light in a certain condition.

Fluorescence Phosphorescence

Flame ReactionFlame Reaction

Flame reaction is a reaction of some elements.

Those elements absorb heat energy in a flame, and emit specific wavelengths of visible light.

Flame reaction is a kind of Fluorescence.

Flame reaction is a reaction of some elements.

Those elements absorb heat energy in a flame, and emit specific wavelengths of visible light.

Flame reaction is a kind of Fluorescence.

Flame ReactionFlame Reaction

Size Quantization EffectsSize Quantization Effects

Fluorescent LampFluorescent Lamp

PhosphorescencePhosphorescence

A process in which light energy absorbed by a substance is stored and released relatively slowly in the form of light.

A process in which light energy absorbed by a substance is stored and released relatively slowly in the form of light.

Glow in the DarkGlow in the Dark

ColorColor

A color of a substance depends on the structure of its molecule or atom.

The transition of electrons in electronic orbital states shows the specific color.

There are many substances that don’t have colors because their transitions occur out of the visible range.

A color of a substance depends on the structure of its molecule or atom.

The transition of electrons in electronic orbital states shows the specific color.

There are many substances that don’t have colors because their transitions occur out of the visible range.