Chemistry 151PowerPoint PresentationSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Chemistry 151Chemistry and Color(from an elementary school perspective)Electromagnetic radiation•Light is a form of energy that travels through space like a wave and is characterized by its wavelength.Electromagnetic radiation•Only certain wavelengths of light can be detected by the human eye.•“White” light is actually composed of all colors in equal amounts.White Light•Specialized cone cells in our eyes respond to visible light and signal color to the brain.Color PerceptionColor Perception•There are three different kinds of human cone cells varying in their sensitivities to different colors of light: blue, green, and red.•Leads to trichromatic color vision.•Sometimes called long, medium and short cones.Color Perception•Birds have four different kinds of cones (one in the UV).•Dogs have only two (no green).Color Perception•Birds have four different kinds of cones (one in the UV).•Dogs have only two (no green).The Bird’s View•A defect in one of the three types of cones leads to “color blindness,” difficulty in distinguishing colors.Color Perception•Objects appear colored when they reflect light of that color.Color Perception•Red cones respond, signalling to the brain that the apple is “red”.•Adding red, green, and blue light in equal amounts leads to white light.Red, green, and blue are the primary colors of light.Color Perception•Adding red, green, and blue light in unequal amounts leads to all possible colors of light.•Pigments are molecules that absorb certain colors of light and reflect the others.•The brain integrates the responses of the cone cells to perceive the pigment’s color.Color PerceptionThe yellow filter absorbs blue light; reflects red and green.•A pigment generally absorbs light that is complementary to that observed.•Absorbance data can be correlated to the identity of pigment.Absorbance of Light•For example: a purple pigment absorbs yellow-green light.Absorbance of LightYellow: 425 nm (absorbs violet)Red: 522 nm(absorbs cyan)Blue: 610 nm(absorbs orange)Absorbance of LightFood Coloring Data:Absorbance of Light•The absorbance of light can be measured with a spectophotometer.•The three primary colors of pigments arise from subtracting out one of the three primary colors of light.Magenta pigment absorbs green light.Absorbance of LightMagenta pigment absorbs green light.Yellow pigment absorbs blue light.•The three primary colors of pigments arise from subtracting out one of the three primary colors of light.Absorbance of LightMagenta pigment absorbs green light.Yellow pigment absorbs blue light.Cyan pigment absorbs red light.•The three primary colors of pigments arise from subtracting out one of the three primary colors of light.Absorbance of Light•Adding magenta, cyan, and yellow pigments in equal proportions leads to black.Magenta, cyan, and yellow are the primary colors of pigments.Color Perception•Adding magenta, cyan, and yellow pigments in unequal proportions leads to all possible colors of pigments.•Equally adding adjacent pigments leads to the development of color wheels.Primary Colors of Pigmentsprimary colors secondary colorstertiary colors•Colors opposite each other on color wheels are complementary colors.Complementary colorscyanredyellowbluemagentagreen•Pigments of complementary colors add in equal amounts to give black.Complementary colorsYellow and blueRed and cyanMagenta and green2012: Color Wheels2012: Color WheelsPrimary and secondary colors are introduced to show that some colors are made when mixing other colors together. Students make their own color wheels using homemade paint.•Paints are a homogeneous mixture of a pigment, which provides color, and a binder, which cements the pigment to the solid support after drying.Colors in artPigments in nature•Early artists had primarily earth tones in their palettes, many mineral-based.charcoal brown ochrehematite (Fe2O3 · nH2O) is a source of red, yellow, and brown ochrecinnabar (HgS) is a source of the red pigment vermilion azurite (2 CuCO3 · Cu(OH)2) Mineral-Based (Inorganic) Pigments2010: Alien Rocks2010: Alien RocksStudents analyze rock samples from the newly discovered planet of Zircondrion to determine if they are similar to Earth minerals. Analysis includes: •Color•Iron? (absorbance of light) Properties such as magnetism and fluorescence•Chemical reactionsPlant & Animal-Based (Organic) PigmentsIndigoMadder lake(alizarin)Tyrian purpleCommon Sources of PigmentsMarigolds Grape JuiceWalnut hulls Kool-AidBeets Cochineal BeetlesCH112: Color Activity CH112: Color Activity Learning Goals:•Investigate the interaction of dyes with different fabrics.•Identify ionic and polar groups in dyes and fabrics.•Identify the different types of bonding interactions between dyes and fabrics.Pigment/Metal Dates in useAzurite/Cu until 1800Ultramarine/Al until 1828Prussian Blue/Fe post-1704Synthetic Ultramarine/Al post-1828Cerulean Blue/Co, Sn post-1850Manganese Blue/Mn post-1935History of blue pigment useThe chemistry of fraud detectionLast Friday, a priceless masterpiece was stolen from the little-known Waterville Museum of Old Weird Art. The painting was the masterpiece of the great Italian finger painter, Alfredo Fettuccini. However, yesterday the caretaker told police he forgot he had taken the painting home to clean it, and found it in his bedroom the next morning. An original painting by Fettuccini and the painting produced by the caretaker have been confiscated, packaged, and sent to the Colby Chemistry Lab for analysis. Alfredo Fettuccini1600 - 16502008: Art Fraud Activity 2008: Art Fraud ActivityYou suspect that the caretaker, Ebenezer Wheezingeezer, stole the real painting and replaced it with a fake. You will investigate the pigments used in the paintings and then look for clues on the paintings themselves. The Waterville Museum of Old Weird Art has granted you special permission to handle these rare paintings. The police are standing by, awaiting your judgment.The case of the missing masterpieceEbenezer Wheezingeezer1950 -