sry using this page to post assignments in IT so i can print i libary
Atomic Number: 14 Atomic Radius: 117 pm
Atomic Symbol: Si Melting Point: 1414 ºC
Atomic Weight: 28.086 Boiling Point: 3265 ºC
Electron Configuration: [Ne]3s23p2 Oxidation States: 2,4,-4
History
(L. silex: silicis, flint) In 1800, Davy thought silica to be a compound and not an element; but in 1811, Gay Lussac and Thenard probably prepared impure amorphous silicon by heating potassium with silicon tetrafluoride.
In 1824 Berzelius, generally credited with the discovery, prepared amorphous silicon by the same general method and purified the product by removing the fluosilicates by repeated washings. Deville in 1854 first prepared crystalline silicon, the second allotropic form of the element.
Sources
Silicon is present in the sun and stars and is a principal component of a class of meteorites known as aerolites. It is also a component of tektites, a natural glass of uncertain origin.
Silicon makes up 25.7% of the earth's crust, by weight, and is the second most abundant element, being exceeded only by oxygen. Silicon is not found free in nature, but occurs chiefly as the oxide and as silicates. Sand, quartz, rock crystal, amethyst, agate, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, hornblende, asbestos, feldspar, clay, mica, etc. are but a few of the numerous silicate minerals.
Silicon is prepared commercially by heating silica and carbon in an electric furnace, using carbon electrodes. Several other methods can be used for preparing the element. Amorphous silicon can be prepared as a brown powder, which can be easily melted or vaporized. The Czochralski process is commonly used to produce single crystals of silicon used for solid-state or semiconductor devices. Hyperpure silicon can be prepared by the thermal decomposition of ultra-pure trichlorosilane in a hydrogen atmosphere, and by a vacuum float zone process.
Uses
Silicon is one of man's most useful elements. In the form of sand and clay it is used to make concrete and brick; it is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc. Silica, as sand, is a principal ingredient of glass, one of the most inexpensive of materials with excellent mechanical, optical, thermal, and electrical properties. Glass can be made in a very great variety of shapes, and is used as containers, window glass, insulators, and thousands of other uses. Silicon tetrachloride can be used as iridize glass.
Hyperpure silicon can be doped with boron, gallium, phosphorus, or arsenic to produce silicon for use in transistors, solar cells, rectifiers, and other solid-state devices which are used extensively in the electronics and space-age industries.
Hydrogenated amorphous silicon has shown promise in producing economical cells for converting solar energy into electricity.
Silicon is important to plant and animal life. Diatoms in both fresh and salt water extract Silica from the water to build their cell walls. Silica is present in the ashes of plants and in the human skeleton. Silicon is an important ingredient in steel; silicon carbide is one of the most important abrasives and has been used in lasers to produce coherent light of 4560 A.
Silcones are important products of silicon. They may be prepared by hydrolyzing a silicon organic chloride, such as dimethyl silicon chloride. Hydrolysis and condensation of various substituted chlorosilanes can be used to produce a very great number of polymeric products, or silicones, ranging from liquids to hard, glasslike solids with many useful properties.
Properties
Crystalline silicon has a metallic luster and grayish color. Silicon is a relatively inert element, but it is attacked by halogens and dilute alkali. Most acids, except hydrofluoric, do not affect it. Elemental silicon transmits more than 95% of all wavelengths of infrared, from 1.3 to 6.y micro-m.
Costs
Regular grade silicon (99%) costs about /home/free/cgi-bin/util/sitebuilder.50/g. Silicon 99.9% pure costs about /lb; hyperpure silicon may cost as much as /oz.
Handling
* Discoverer: J"ns Berzelius
* Discovery Location: Sweden
* Discovery Year: 1823
* Name Origin:
Latin: Latin: silex (flint).
* Sources:
Silicon is the second most abundant element and comprises 25% of the earth's crust. Makes up major portion of clay, granite, quartz (SiO2), and sand.
* Uses:
Used in glass as silicon dioxide (SiO2). It is used as a semiconductor to make microchips for electronics (like your computer). Silicon is also used in solar cells, tools, cement, grease and oils.
* Additional Notes:
Silicon carbide (SiC) is one of the hardest substances known.
Miners, stonecutters, and others engaged in work where siliceous dust is breathed into large quantities often develop a serious lung disease known as silicosis.
Title Picture: Alchemical symbol for silicon.
Davy failed to decompose silica using a voltaic pile or by passing Potassium vapor over red-hot silica. Gay-Lussac and Thenard obtained a reddish brown powder after violently reacting silicon tetrafluoride and Potassium. Berzelius persisted to purify the French powder in 1824 obtaining a brown amorphous substance by two different techniques. Silicon (Si = #14): Silex (Latin) is flint, a hard stone. Silicon was identified in flint, SiO2. The suffix -on was added because of its resemblance to Carbon. Question:
What is the second most abundant element on earth (after oxygen)?
Answer:
silicon
Physical Properties of Silicon
Help on Cleavage: Cleavage: None
Help on Color: Color: Iron black, Reddish brown.
Help on Diaphaniety: Diaphaniety: Opaque
Help on Fracture: Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Help on Habits: Habits: Anhedral Grains - Granular minerals without the expression of crystal shapes, Microscopic Crystals - Crystals visible only with microscopes.
Help on Hardness: Hardness: 7 - Quartz
Help on Luster: Luster: Metallic
Help on Streak: Streak: black
Electron Density:
relectron=2.32 gm/cc
note: rSilicon =2.33 gm/cc.
Help on Photoelectric: Photoelectric:
PESilicon = 3.34 barns/electron
U=PESilicon x relectron= 7.76 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Silicon is Not Radioactive
IT Review comming soon.
Which boot function moves MDR in RAM: primary bootstrap
Thickness of PCMCA cards?
Know how to convert HEX to DECIMAL and DECIMAL to HEX.
What program do you use to define primary and extended partitions? F-Disk
Voltages of ATX P/S.
What do you use to test voltage? Multi meter
Name some input devices? Keyboard Mice scanner
Procedure to load system property pamphlets ( 9x)?
When the OS (9X) which utility can be used to skip driver? Asd.exe
Skuzzy controllers (ID’s)?
Controller card: 7
Location for conventional memory 0-640 kb
Type of connector at end of telephone cable? RJ-11
Which widows (3.1) files were replaced by windows (9) registry database? INI files
IRQ’s ? ( what uses particular IRQ) IRQ for primary IDE controller:
Color depth? ( color depth of 1) MONOCHROME
RIM MODULE?
IDENIFY spots on MOBO!
Which DOS commands or files contains internal DOS commands? Command.com
Need to know where best place to mount hard drive in a. case.
If you replace your video card with a. newer faster Video Card what should you do with the presently installed drivers? Replace them with Windows Basic Driver then install new drivers.
If you replace a. hard drive and turn on power but light on hard drive isn’t lit up what problem. Cable going to LAD not connected to hard drive or mother board.
25 pin connector on back of computer? Parallel
Light for floppy continues to stay on, what’s the problem? The. Ribbon cable is upside down.
How do you get to CMOS set-up? Depends on brand of computer
If you have parallel serial USB firewire interface on comp. Which is. Hot swappable? USB.
Which expansion slot is. Used just for video?
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CD rom speed what it in multiple of(8x)? 8 times x is. 150 k bits per second.
What do you call combination of text sound and video? Multi media
What kind of fault is. It called when computer freezes? General Protection Fault
Which file would load HIMEM.SYS EMMI.SYS? config.sys
Where would you go to view information such as OS Properites? System properties
Convert binary to Decimal… 1101110 = 214
D to B 236> ?
Regedit used to display registry
Name of log file 98 uses during set up? Setuplog.txt
What type of memory is cash? RAM
How many FAT tables are created on HD? 2
How do you repair MDR? FDISK/
8 dot symbol for DOS 12345678.123 ( 8 characters 3 ext.)
Can’t use any special characters in DOS format
DOS not user friendly
INTERFACE is. Command prompt line.
What #bering system does computers primarly use ( binary)
How many substitute SIM banks in a. computer
Boot drive should be? Primary master
Know how to convert hex to binary B9 >
|
0-0000 |
8-1000 |
|
1-0001 |
9-1001 |
|
2-0010 |
A.-1010 |
|
3-0011 |
B-1011 |
|
4-0100 |
C-1100 |
|
5-0101 |
D-1101 |
|
6-0110 |
E-1110 |
|
7-0111 |
F-1111 |
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Number of pins on IDE cable? 40
On your floppy drive cable one end has a. twist 2 it. Which one should it be connected to?
