Uses of Silicon. Silicone Implants - Periodic Table of Videos. Silicones - environmental impact. Thanks for your responses to last week's question - Why do you avoid silicones? There are four major reasons... 1. Environmental impact of silicones; 2. Environmental impact of the manufacturing process; 3. 4. I didn't think about the environmental impact point, so here's a little research I've done... From the Polymeric Materials Encyclopedia: "A generally accepted conclusion is that methyl silicates and silicone polymers have no known negative environmental impact. " From The Principles of Polymer Science in Cosmetics and Personal Care: (Summary) Due to extremely low water solubility and high vapour pressure, silicones are not found in any appreciable extent in soil or water, and they may actually reduce the creation of ground ozone. I found a press release from Dow Corning talking about the environmental impact of silicones, but I'm excluding this one because it is going to be self-serving.
So on the surface it would appear that silicones are considered safe for the environment. The Environmental Literacy Council - Silicon. Silicon is the second most abundant element in the Earth's crust, after oxygen. It has atomic number 14, and occurs in the same group as carbon in the periodic table. Most rock consists of compounds of silicon, and sand consists largely of silica, or silicon dioxide (SiO2). Silicon dioxide occurs in two forms: a crystalline form, quartz, which has the same lattice structure as diamond, and a noncrystalline form, flint. Sand consists largely of small quartz crystals.
Many varieties of colored gemstones, such as amethyst, are quartz crystals with colored impurities. Pure, elemental silicon does not occur in nature because it is highly reactive, tending to form compounds with other elements. It must be prepared artificially. SiO2 + 2C ----- Si + 2CO A byproduct of this reaction is carbon monoxide (CO). Pure silicon has the physical properties of both a metal and a nonmetal. As a semiconductor, silicon has taken on enormous significance in the electronics industry. What are some uses for Silicon. Silicon - Uses, Pictures, Characteristics, Properties, Periodic Table. Characteristics: Silicon is a hard, relatively inert metalloid and in crystalline form is very brittle with a marked metallic luster.
Silicon occurs mainly in nature as the oxide and as silicates. The solid form of silicon does not react with oxygen, water and most acids. Silicon reacts with halogens or dilute alkalis. Silicon also has the unusual property that (like water) it expands as it freezes. Four other elements expand when they freeze; gallium, bismuth, antimony and germanium Uses: Silicon chips are the basis of modern electronic and computing.
Silicon is alloyed with aluminum for use in engines as the presence of silicon improves the metal's castability. Silicon carbide, more commonly called carborundum, is extremely hard and is used in abrasives. Silica (SiO2) in sand and minerals in clay is used to make concrete and bricks. Pure, crystalline silicon dioxide (quartz) resonates at a very precise frequency and is used in high-precision watches and clocks. Silicon Facts - Periodic Table of the Elements. Silicon - Element information, properties and uses | Periodic Table. (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry (End promo) Meera Senthilingam For this week's element we enter the world of science fiction to explore life in outer space.
Here's Andrea Sella. Andrea Sella When I was about 12, my friends and I went through a phase of reading science fiction. I was reminded of these readings a couple of weeks ago when I went to see an exhibition of work by a couple of friends of mine. Silicate rocks - those in which silicon is surrounded tetrahedrally by four oxygen atoms - exist in an astonishing variety, the differences being determined by how the tetrahedra building blocks link together, and what other elements are present to complete the picture. The purest of these chain-like materials is silicon dioxide - silica - found quite commonly in nature as the colourless mineral quartz or rock crystal. But what of the element itself? Simon Cotton. Silicon: Say It.
Silicon. Silicon is a chemical element with the symbol Si and atomic number 14. It is a tetravalent metalloid, less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table. Controversy about silicon's character dates to its discovery; it was first prepared and characterized in pure form in 1823.
In 1808, it was given the name silicium (from Latin: silex, hard stone or flint), with an -ium word-ending to suggest a metal, a name which the element retains in several non-English languages. However, its final English name, first suggested in 1817, reflects the more physically similar elements carbon and boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure free element in nature. Elemental silicon also has a large impact on the modern world economy. Characteristics[edit] Physical[edit] Silicon is a semiconductor. Chemical[edit] The Element Silicon.
[Click for Isotope Data] Atomic Number: 14 Atomic Weight: 28.0855 Melting Point: 1687 K (1414°C or 2577°F) Boiling Point: 3538 K (3265°C or 5909°F) Density: 2.3296 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Semi-metal Period Number: 3 Group Number: 14 Group Name: none What's in a name? Say what? History and Uses: Silicon was discovered by Jöns Jacob Berzelius, a Swedish chemist, in 1824 by heating chips of potassium in a silica container and then carefully washing away the residual by-products. Two allotropes of silicon exist at room temperature: amorphous and crystalline. Silicon dioxide (SiO2), silicon's most common compound, is the most abundant compound in the earth's crust. Silicon forms other useful compounds.
Estimated Crustal Abundance: 2.82×105 milligrams per kilogram Estimated Oceanic Abundance: 2.2 milligrams per liter Number of Stable Isotopes: 3 (View all isotope data) Ionization Energy: 8.152 eV Oxidation States: +4, +2, -4.