CHEMISTRY IN COMPUTERS 2 ND PERIOD MEYER

Wait there’s chemistry in computers? Duh there’s and l.woodbridge.hs.groupfusion.net/modules/groups/integrated_home.phtml?gid= &sessionid=ad9a10e1e43c6cc7bac672a3e29759aa right … ? l.woodbridge.hs.groupfusion.net/modules/groups/integrated_home.phtml?gid= &sessionid=ad9a10e1e43c6cc7bac672a3e29759aa Well actually…… + =

BRIEF HISTORY OF CHEMISTRY IN COMPUTERS John Bardeen, Walter Brattain, and William Shockley create the first transistor in 1947 Replaced the bulky, fragile vacuum tubes that had been amplifying and switching signals What is a transistor though?

TRANSISTORS Function-On and Off Switch Transistors: Advantages Usually lower cost and smaller than tubes, especially in small-signal circuits. Can be combined in the millions on one cheap die to make an integrated circuit, whereas tubes are limited to at most three functional units per glass bulb. Lower power consumption, less waste heat, and high efficiency than equivalent tubes, especially in small-signal circuits. Can operate on lower-voltage supplies for greater safety, lower costs, tighter clearances. Matching transformers not required for low-impedance loads. Usually more physical ruggedness than tubes (depends upon construction).

THE TRANSFER TO SILICON Germanium dioxide(insulator form) One strange and very useful property Structure allow passage of electrical current to be uniform Valence Electrons and orbital Natural State of Purified Silicon

DOPING OF SILICON Doping of Silicon to push semi –conductivity one way or another

EVOLUTION OF COMPUTERS The problems with using silicon as computers are getting smaller and faster Titanium to cobalt to nickel Problems with changing metals in a transistor

STORING OF DATA Hard drive is storing ones and zeroes in magnet to store data Metal alloy coating of cobalt, chromium, and platinum.

CHEMISTRY IN OUR CELL PHONE BATTERIES Electromagnetic reactions between the anode, cathode and electrolyte Types of Batteries Zinc-carbon battery: The anode is zinc, the cathode is manganese dioxide, and the electrolyte is ammonium chloride or zinc chloride. Alkaline battery: The cathode is composed of a manganese dioxide mixture, while the anode is a zinc powder. It gets its name from the potassium hydroxide electrolyte, which is an alkaline substance. Lithium-ion battery (rechargeable): Lithium chemistry is often used in cell phones, digital cameras and even electric cars. A variety of substances are used in lithium batteries, but a common combination is a lithium cobalt oxide cathode and a carbon anode. Lead-acid battery (rechargeable): This is the chemistry used in a typical car battery. The electrodes are usually made of lead dioxide and metallic lead, while the electrolyte is a sulfuric acid solution.

CATHODE RAY TUBES Philo Farnsworth first introduced the use for monitors in 1927 Form an image by rapidly scanning an electron beam across them Chemists found thousands of formulas. Properly mixed, Zinc sulfide with copper and aluminum glows green; with silver, it makes blue. One red brew uses europium, oxygen, and Yttrium Problems with the CTR

TRANSITION TO LIQUID CRYSTAL DISPLAY James Fergason in 1971 make the first practical LCD LCDs bring thinner monitors that use less power, and they also bring entirely new chemistry White light passed through first filter twists enough going through the liquid crystals to pass through the second. Applying an electric field to the column untwists it, and the light is blocked. Red, green and blue filters over individual pixels produce color. No electron gun is needed, reducing power needs and display size. Because the screen is constantly lit, it doesn’t flicker.

QUESTIONS 1)Based off the knowledge of how to dope silicon to become a conductor, which of the following would not be appropriate to use? A: Boron B: Arsenic C: Sulfur D: Phosphorus 2) Which problem did liquid crystal displays NOT fix? A: Less power usage B: Portability C: Display size D: Flickering issue

SOURCES computing/ computing/ transistors-compared/ transistors-compared/