Group 1 alkali metals and compounds
Group 1 metals are reactive. When they react with water, they form hydroxides along with hydrogen gas. An example of hydroxide formed by a alkali metal is sodium hydroxide, which are strong bases commonly used in industries.
When alkali metals are subjected to flame test, different metals of this group gives different flame colours. Electronic transitions occur within the metal atoms and ions formed in the flames with energies , that emit light of very specific frequency and fall in the visible parts of the spectrum which give a characteristic colour to the flame. When an alkali metal salt is introduced to a Bunsen burner flame, a characteristic colour is observed. (Li – red, Na – golden- yellow, K – lilac). Hence, these properties of alkali metals can be used for analysis of metal compounds and pyrotechnics (fireworks).
Lithium
Lithium is usually found in small amounts in Earth’s surface. It is found forming compounds with aluminum. Most people know lithium best because of its use (in the form of lithium carbonate) as a way of controlling certain mental disorders. Lithium is indicated in the treatment of manic episodes of Bipolar Disorder. Bipolar Disorder, Manic (DSM-III) is equivalent to Manic Depressive illness can often benefit from regular treatments with lithium carbonate. Lithium is also used industrially in lubricants, batteries, glass, and alloys (mixtures of metals) with lead, aluminum, and magnesium.
Sodium
Sodium is the seventh most abundant element in Earth’s surface. It occurs commonly in Earth’s oceans in the form of sodium chloride and in crustal rocks as sodium chloride, sodium carbonate, sodium nitrate (saltpetre), sodium sulfate, and sodium borate (borax).
Compounds of sodium are among the most important in all of the chemical industry. Sodium chloride (table salt) is widely used chemicals in the world. It also has many industrial uses, such as serving as a raw material in the manufacturing of other chemicals. Sodium nitrite is a principle ingredient in gunpowder. The pulp and paper industry uses sodium compounds such as sodium hydroxide, sodium carbonate, and sodium sulfate; the latter is utilized in the production of cardboard and brown paper. Sodium carbonate is used by power companies to absorb sulfur dioxide, a serious pollutant, from smokestack gases. It is also important to the glass and detergent industries. Sodium hydroxide is one of the top ten industrially produced chemicals, heavily used in manufacturing. Sodium bicarbonate (baking soda) is produced for the food industry as well. Sodium is known to control nerve transmission and excessive use of sodium may lead to high blood pressure.
Image obtained from (www.celiac-scoop.com)
Potassium
Potassium is found most commonly in the form of the chloride, potassium chloride. It is present both in sea water and as a mineral known as sylvite in Earth’s crust. Almost all the potassium used industrially goes into fertilizer. Other important compounds of potassium include potassium hydroxide, used in the manufacture of detergents; potassium chlorate, used for the production of explosives; and potassium bromide, an essential chemical in photography. Like sodium, potassium is a vital nutrient for organisms in a variety of ways. Potassium levels are naturally high in vegetables and fruits, and sodium levels are naturally low. Potassium is a mineral that your body needs to function properly. It is a type of electrolyte.A low blood level of potassium is called hypokalemia. It can cause weak muscles, abnormal heart rhythms, and a slight rise in blood pressure.
Sylvite crystal. Image obtained from( www.mtholyoke.edu )
Rubidium, Cesium and Francium
Rubidium and cesium are much less common than are sodium and potassium. Both elements also have relatively few practical applications. Rubidium is employed primarily in various kinds of chemical research. Rubidium Chloride has been used to treat patients with depression. In addition, some kinds of glass and radiation detection equipment are made with cesium compounds.
Cesium has a limited number of uses. One is as a getter in bulbs and evacuated tubes. The bulb must be as free from gases as possible to work properly. Small amounts of cesium react with any air left in the bulb. It reacts with the gas to form a solid cesium compound. Cesium is called a getter because it removes gases out of the bulb.
Cesium is also used in photoelectric cells, devices for converting sunlight into electrical energy. When sunlight shines on cesium, it excites or energizes the electrons in cesium atoms. The excited electrons easily flow away, producing an electric current.
An important use of cesium today is in an atomic clock. An atomic clock is the most precise method now available for measuring time.
http://www.swissworld.org/typo3temp/pics/d28b55938e.jpg
Francium is a radioactive element (one that spontaneously gives off energy in the form of particles or waves by disintegration of their atomic nuclei) and is one of the rarest elements in Earth’s surface.
Group 2 alkali earth metals and compounds
Similar to group 1 elements, the group 2 elements subjected to flame test will burns to gives different colour too. (Ca-orange-red, Sr-red, Ba-pale green).
Beryllium
Beryllium occurs most commonly in gemstones and beautiful minerals such as beryl (Be3Al2(SiO3)6 ), emeralds, and aquamarine.
http://en.wikipedia.org/wiki/File:Beryl09.jpg
The most important industrial application of beryllium is in the manufacture of alloys (metal mixtures). Beryllium is added in small amount to increase strength, durability, and temperature stability to alloys. Copper-beryllium alloys make good hand tools in industries that use flammable solvents because the tools do not cause sparks when struck against other objects. Nickel-beryllium alloys are used for specialized electrical connections and various high temperature applications. Beryllium is used instead of glass in X-ray tubes because it lets through more of the X-radiation than glass would.
Beryllium is toxic to humans. Exposure to high concentrations can cause a pneumonia-like condition that may result in death. Long-term exposure to even small concentrations can have serious health problems, such as a respiratory problem known as berylliosis. Berylliosis is the chronic allergic-type lung response and chronic lung disease caused by exposure to beryllium.
Magnesium
Magnesium a common element in Earth’s crust. It occurs in minerals such as dolomite, magnesite, carnallite, asbestos, soapstone, mica, and spinel. The oceans also contain relatively high concentrations of magnesium chloride.
Magnesium performs a critical role in living things because it is a key component of chlorophyll. Chlorophyll is the green pigment that convert the energy from the sunlight into stored energy or chemical energy in plant sugars during photo-synthesis. (Through the process of photosynthesis, plants use light to break down chemical compounds). Chlorophyll is a large molecule called a porphyrin; the magnesium occupies the center of the porphyrin molecule.
Image obtained from www.bio.miami.edu
Elemental magnesium is a strong, light metal, particularly when alloyed, or mixed, with other metals like aluminum or zinc. These alloys have many uses in construction, such as in the manufacture of airplane.
Calcium
Some of the uses of group 2 alkali earth metals is limewater. It is used to cleans waste gases from industries. For instance, Waste gases from industries containing SO2 can be cleaned by bubbling through limewater, This process is called sulfation, in which the toxic sulfur dioxide is trapped as a precipitate(white precipitate):
- Ca(OH)2(aq) + SO2(g) → CaSO3(s) + H2O(l)
CO2 can also be removed using limewater too.
Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
Lime softening, also known as Clark’s process, is a type of water treatment used for water softening which uses the addition of limewater (calcium hydroxide) to remove hardness (calcium and magnesium) ions by precipitation.
Next, alkali earth metal compounds such as Monocalcium phosphate with the chemical formula Ca(H2PO4)2 is used in baking soda.Calcium dihydrogen phosphate is used in the food industry as a leavening agent. This causes baking goods or bread to rise when place at high temperature.
These are the industrial applications of calcium. Marble is also a good building material. Limestone and dolomite are the principle sources of slaked lime (calcium hydroxide) and quick lime (calcium oxide) for the steel, glass, paper, dairy, and metallurgical industries. Lime can act as an agent to remove impurities from steel, as a neutralizing agent for acidic industrial waste, as a reagent (a chemically active substance) for reclaiming sodium hydroxide from paper pulping waste, and as a scrubbing compound to remove pollutants from smokestack effluent. The paper industry uses calcium carbonate as an additive to give smoothness and opacity (the opposite of transparency) to the finished paper. Calcium are also found in various food, cosmetic, and pharmaceutical industries use it in antacids, toothpaste, chewing gum, and vitamins.
Strontium, Barium and Radium
Strontium and barium occur in very small concentrations in the oceans. Radium is a radioactive element that occurs only in association with uranium, from which it is formed by radioactive decay. (A radioactive element is one that spontaneously gives off energy in the form of particles or waves by disintegration of their atomic nuclei.) This relationship between uranium and radium is used in radiometric dating. The larger the amount of radium in a rock, the longer decay has been taking place and the older the rock is.
Because of the brilliant red color they produce when burned, strontium compounds are widely used in fireworks. Strontium carbonate is also a glass additive, and strontium hydroxide is a refining agent in the production of beet sugar. The most important commercial application of barium is in the form of barium sulfate, used as a lubricating mud in well-drilling operations. In the medical field, patients with gastrointestinal (stomach and intestinal) problems are often required to drink a chalky, white liquid form of barium sulfate before having X-ray examinations.
Radium was formerly used in treatment for various kinds of cancer and other conditions. Compounds of radium were also used to paint the luminous numbers on watch dials. That application has been stopped because of the health risks to workers who used the radium paint.
Groups 3- 12 (Transition metals) and compounds
The d-block transition elements have great importance in our lives. These elements contain electrons in their d-orbitals, allowing them to be able to lose a multiple number of d orbital electrons, and hence have multiple oxidation states. A good example is copper which has two common oxidation states +1 and +2. It is this property that causes d-block metals to make great catalysts, such as iron being used as one in the production of ammonia in the Haber process.
Most transition metals are good electrical conductors, and are also malleable, ductile, and lustrous. An example of such a metal is gold; a rare metal used as electrical conductors in circuits in computers and other electrical devices and is sold at extremely high prices in the jewelry industry, such along with silver.
These metals can also mix easily to form alloys due to all the d-block metals in the same period have similar atomic sizes. When two or more metals mix, we call the new metal an alloy. Brass is a good example of an alloy, which is made from mixing copper and zinc combined. Another example of such an alloy would be steel, an alloy iron, which is used to make bridges, buildings, and also works of art as well as being employed the aerospace industry.
Group 13: The Boron Family
The Group 3A (Boron Group) comprises of Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), Thallium(Tl), Ununtrium (Uut). The Group III elements are the first to distinguish non-metallic and metallic character in the group. Given their odd number of electrons and inability to form four bonds to achieve an octet configuration, they have remarkable uses.
Boron
Boron have a variety of allotropes such as B12. Boron is actually extracted from the earth as Na2B4O7 (borax). The red color of the material is due to an iron contaminant.
Applications:
B(OH)3 is a Lewis acid, boric acid which is often used to kill pests. Boron also forms some very interesting compounds with nitrogen called boron nitrides which have the same electronic configuration as graphite and C60 and consequently have prompted a lot of interest in them for new materials.
2B + 2NH3-> 2BN + 3 H2
Aluminium
Aluminium is the most abundant element found in the earth’s crust. It is mined as Bauxite, an impure aluminum oxide, and turned into alumina (Al2O3) by the Bayer process. To produce Al in an inexpensive way, the Hall process is used. Aluminum is removed from the earth as Na3AlF6,cryolite, melted with Alumina in an electrochemical process with the following overall reaction to produce metallic Al
4Al+3 + 6O-2 + 3C-> 4Al + 3CO2
Applications:
Aluminum is an important element used for manufacturing, mainly the production of paper. Aluminum sulfate is known as papermaker’s alum.
Al2O3 + H2SO4 -> Al2(SO4)3 + 3H2O
Aluminum oxides are also the basis of many valuable gems when combined with trace metals.
Ruby, Sapphire and Topaz
Group 14: Carbon family and compounds
The allotropes of carbon are diamond, graphite and fullerenes. Diamond is one of the hardest solids known and it has high melting point (4000 degree Celsius, in the absence of O2) of nay element. The crystal lattice of diamond consist of tetrahedral sp3 carbon atoms.
Graphite is a slippery and soft and has a flaky appearance. Graphite consists of planar layers of hexagons formed by sp2 hybridized carbons. The delocalization of electrons in the C-C π-bonds leads to its electrical conductivity. The average C-C bond distance is 1.42Ă in graphite. Graphite is thermodynamically more stable than diamond by 2.9kJ/mol.
Fullerenes, on the other hand, are isolated by the extraction od specially prepared soot with organic solvents. The most common fullerene is C60 ( Buckminster Fullerene ) which is a molecule that is formed by sp2 carbons.
Buckminster Fullerene image obtained from www.3dchem.com
Another element of the group is silicon in which many important silicate minerals are known. One of them is Talc which is a mineral composed of hydrated magnesium silicate with the chemical formula Mg6 . Due to its softness and other special characteristics, talc has an important function in several products: Body powder, pharmaceutics, makeup, paper, paint and ceramics
Group 15: The Nitrogen Family
The nitrogen family includes nitrogen (N), phosphorus (P), arsenic (As),antimony (Sb), and bismuth (Bi). All Group 15 elements have the electron configuration ns2np3 in their outer shell, where n is equal to the principal quantum number. The nitrogen family is located in the p-block in Group 15.
Nitrogen
Nitrogen is mainly used in the production of ammonia (NH3). Large amounts of nitrogen are combined with hydrogen to produce ammonia in a method known as the Haber process. Large amounts of ammonia are then used to create nitric acid (HNO3) through the Ostwald process. This caters to the high demand of nitric which is used in the making of fertilizers and explosives.
Nitrogen gas is largely inert and is used as a protective shield in the semiconductor industry and during certain types of welding and soldering operations. During the welding process, oxides will naturally form in steel and this weakens the weld. Hence, nitrogen is used to exclude oxygen during welding, resulting in better welds. Oil companies use high pressure nitrogen to help force crude oil to the surface. Liquid nitrogen being an inexpensive cryogenic liquid, is used for refrigeration, preservation of biological samples and for low temperature scientific experimentation.
Nitrogen is also present in virtually all pharmacological drugs. In the form of nitrous oxide, it is used as an anesthetic. Cryopreservation also uses nitrogen gas to conserve egg, blood, sperm and other biological specimens. The CPUs in computers use nitrogen gas to keep them from heating up.
In the natural world, the nitrogen cycle is vital to living organisms. Nitrogen is taken from the atmosphere and converted to nitrates through lightning storms and nitrogen fixing bacteria. The nitrates fertilize plant growth where the nitrogen becomes bound in amino acids, DNA and proteins. It can then be eaten by animals. Eventually the nitrogen from the plants and animals returns to the soil and atmosphere and the cycle repeats.
Phosphorous
Phosphorus is the eleventh most abundant element, making up 0.11% of the earth’s crust. The main source of phosphorus compounds is phosphorus rocks. Phosphorous is often found in the form of apatite ores. These include compounds such as fluorapatite (Ca5(PO4)3F), which in fluoridated water is used to strengthen teeth, and hydroxylapatite (Ca10(OH)2(PO4)6), a major component of tooth enamel and bone material.
The most common allotropic forms of Phosphorous are white phosphorus (toxic) and red phosphorous (non-toxic). Both white and red phosphorus are incendiary and have been used to make match tips. Phosphorus trichloride (PCl3) is used in soaps, detergents, plastics, synthetic rubber nylon, motor oils, insecticides and herbicides; phosphoric acid, H3PO4, is used in fertilizers; phosphorus is also used in the food industry, such as in baking powders, instant cereals, cheese, the curing of ham, and in the tartness of soft drinks.
Group 16: Chalcogens and compounds
One of the elements in chalcogens that has a common application in society is Sulfur. The stable elemental form of sulfur is called the orthorhombic sulfur because of the crystalline structure being adopted. The crystal unit cell contains crown shaped S8 molecules stacked in a complex array.
One common application of sulfur is the sulfuric acid that is usually used in chemical experiments. Sulfuric Acid is manufactured by the contact process : SO2 mixed with air is passed over a V2O5 catalyst where upon it is oxidized to SO3. As SO3 could not be satisfactorily absorbed by water, it is treated with 98% concentrated H2SO4 to form a fuming liquid called the oleum (disulfuric acid H2S2O7) which is then carefully diluted with water to give sulfuric acid. The pure sulfuric acid is an colorless and oily liquid.
Group 17: Halogens
Fluorine
Fluorine is one of the most dangerous chemicals known. It attacks the skin and throat, causing serious burns and respiratory problems at very low concentrations. It is also very reactive chemically. Fluorine can act as an oxidizing (burning) agent in rocket fuels. The vast majority of fluorine, however, is used to make compounds. One of the most interesting of those compounds is hydrofluoric acid (HF). This compound has been used to etch glass. One of the most familiar applications of fluorine compounds is in toothpaste additives. Scientists have discovered that the addition of tiny amounts of fluoride in a person’s diet can decrease the number of dental caries (cavities) that develop. For many years, the most important group of fluorine compounds used commercially were the chlorofluorocarbons (CFCs). The CFCs were used as refrigerants, propellant in spray cans.
In the 1980s, however, scientists found that CFCs break down in the atmosphere. The chlorine formed as a result of this breakdown attacks the ozone layer in Earth’s stratosphere. The loss of the ozone layer is a serious problem for humans since ozone screens out radiation that causes skin cancer and other damage to plants and animals on Earth. Today, scientists are exploring the use of another class of fluorine compounds—the hydrochlorofluorocarbons, or HCFCs—as replacements for CFCs.
Image obtained from www.epa.gov
Chlorine
www.geocaching.com
Chlorine is found abundantly in sodium chloride, which is obtained from seawater and from underground deposits of rock salt formed from seas that have dried up. To obtain pure chlorine, electrolysis is carried out on a water solution of sodium chloride.
Chlorine is used in the bleaching of paper, pulp, and textiles. Chlorine is added to pools and spas to kill bacteria in water that might otherwise cause disease. The process of adding chlorine to a swimming pool is called chlorination. Chlorination is used in disinfection in water supply. Chlorine is used in the preparation of a large variety of compounds, including organic chlorides that are the starting point in the manufacture of plastics and other kinds of polymers (chemical compounds that consist of repeating structural units). One of the most significant of these polymers is polyvinyl chloride (PVC), from which plastic pipe and many other plastic products are made. Another is neoprene, a synthetic form of rubber that is resistant to the effects of heat, oxidation, and oils. Neoprene is widely used in automobile parts.
Bromine
Like chlorine, bromine can be used as a disinfectant. In fact, some water treatment systems have converted from chlorination to bromination as a way of purifying water. One of the most important compounds of bromine was ethylene dibromide, an additive in leaded gasolines. Since leaded gasoline has been removed from the market to reduce pollution to the environment, the use of ethylene dibromide has declined. The product in which most people are likely to encounter compounds of bromine is in photographic film. Tiny crystals of silver bromide undergo a chemical change when exposed to light. This change is responsible for the image produced when photographic film is used to take a picture. Bromine is also used to make a number of organic products that function as pesticides (methyl bromide). Methyl bromide is used as a spray in agricultural crops to prevent pests.
Iodine
As with chlorine and bromine, iodine is obtained from seawater. The human body uses iodine to make thyroxine, an important hormone (chemical messenger) produced by the thyroid gland. (The thyroid is a gland plays an important role in metabolism. Metabolism shows how fast the body convert or burn energy from food.). Iodine is also used commercially in a variety of products including dyes, unique soaps, film, medicines, lubricants, photographic and pharmaceuticals.
Astatine
Astatine is generally regarded as one of the rarest naturally occurring elements. Astatine is radioactive. Astatine longest half life has a half-life of 8.3 hours. This means that half of a sample of the element disappears in 8.3 hours. Astatine is so rare and has such a short half-life, astatine is one of the most poorly understood of the element. It has no practical applications at this time.
Group 18: Noble gases
Helium
Helium gas is much less dense than air and it is often used in balloons and blimps due to its low density. Helium also has its application in technology due to its low boiling point. Divers breathe an artificial oxygen-helium mixture to prevent the formation of gas bubbles in the blood as they swim to the surface from great depths.The barcode scanners in stores use helium-neon lasers to scan barcodes and transmit the information to the computer. The neon gas creates the light when the atoms are excited. However, if the atoms lose their energy, the laser will no longer work. The helium that is located within the laser does not decay quickly and contain a high level of energy, which is then used to re-excite the neon atoms to keep the laser burning.
Neon
Neon Lighting image obtained from techandscience.com
Neon is used in advertising signs. Glass tubes of light are filled with neon together with other gases such as helium under low pressure and are submitted to electrical discharges. Electric discharge produces high-energy electrons that hit the neon atoms changing their energy state, thereby causing the tubes to emit light. Only the red signs actually contain pure neon. Others contain different gases to give different colours. Neon is also used in lightning arrestors. Neon and other noble gases require a high voltage to conduct electricity. Under normal conditions, current will not flow across them. However, a direct lightning strike on places such as a radio tower antenna will cause the neon to arc and conduct the massive amount of electricity to the ground, protecting transmitters and other equipments. Other commercial uses for Neon include high-voltage indicators, TV tubes and helium-gas lasers.
Argon
Argon is a noble gas which does not react with other elements under normal circumstances. Hence it is used as a shield gas during welding. Welding is a process in which two metals are melted under high temperatures and are joined together. During this process, the hot weld needs to be shielded from oxygen because it will oxidize the metal and make it brittle. Hence, argon is added to protect the metal from reacting with oxygen in the air and to prevent the atmosphere from contaminating the weld area. Argon also has its uses in the making of special alloys and manufacturing of titanium. During manufacturing of steel in a converter, addition of argon reduces chromium losses and the desired carbon content can therefore be achieved at a lower temperature.
Argon is also used in light bulbs. The very thin metal filament inside the bulb would react with oxygen and burn away if the bulb were filled with air instead of argon. Argon stops the filament burning away because it is unreactive. Given the inert nature of the gas, argon is also used to provide a protective atmosphere for old documents so as to prevent their degradation during display and storage.
Krypton
Ionized Krypton gas has a whitish appearance due to multiple emission lines. Light bulbs made with ionized Krypton gas are brilliant white light sources useful in high-speed photography, flash bulbs and high-powered airport runway lights. Krypton gas is also used in energy saving fluorescent lights and an inert filling gas in incandescent bulbs. Combined with other gases Krypton gas can be used to make luminous signs that glow with greenish-yellow light. Krypton is also used as a component in lasers as it has high light power density in the red spectral line region.
References
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3. Potassium is a mineral that your body needs to work properly. It is a type of electrolyte. New York Times Health Guide. Retrieved 15-03-2015 from: http://www.nytimes.com/health/guides/nutrition/potassium-in-diet/overview.html
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