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Periodic Table By: Sierra Blankenship. Hydrogen .
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Hydrogen • Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about 90% of the universe by weight. Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. Hydrogen is the lightest gas. Hydrogen gas was used in lighter-than-air balloons for transport but is far too dangerous because of the fire risk (Hindenburg). It burns in air to form only water as waste product and if hydrogen could be made on sufficient scale from other than fossil fuels then there might be a possibility of a hydrogen economy. • Note that while hydrogen is normally shown at the top of the Group 1 elements in the periodic table, the term "alkaline metal" refers to the Group 1 elements from lithium downwards and not hydrogen.
Helium • Helium is one of the so-called noble gases. Helium gas is an unreactive, colorless, and odorless monoatomic gas. Helium is available in pressurized tanks. • Helium is the second most abundant element in the universe after hydrogen. α-particles are doubly ionized helium atoms, He2+. • Helium is used in lighter than air balloons and while heavier than hydrogen, is far safer since helium does not burn. Speaking after breathing an atmosphere rich in helium results in a squeaky voice (don't try it!). • Helium is present in the atmosphere at about 0.0005% (1 part in 200000) by volume and is an important component within hydrocarbon gases in the USA. Its origin in these gases is traced to the decay of radioactive elements in rocks.
Lithium • Lithium is a Group 1 (IA) element containing just a single valence electron (1s22s1). Group 1 elements are called "alkali metals". Lithium is a solid only about half as dense as water and lithium metal is the least dense metal. A freshly cut chunk of lithium is silvery, but tarnishes in a minute or so in air to give a grey surface. Its chemistry is dominated by its tendency to lose an electron to form Li+. It is the first element within the second period. • Lithium is mixed (alloyed) with aluminum and magnesium for light-weight alloys, and is also used in batteries, some greases, some glasses, and in medicine. • Lithium does not occur as the free metal in nature because of its high reactivity. Deposits are known all around the world. It is a minor component of nearly all igneous rocks and is a component of many natural brines.
Beryllium • Beryllium is a Group 2 (IIA) element. It is a metal and has a high melting point. At ordinary temperatures, beryllium resists oxidation in air. Beryllium compounds are very toxic. Its ability to scratch glass is probably due to the formation of a thin layer of the oxide. Aquamarine and emerald are precious forms of the mineral beryl, [Be3Al2(SiO3)6]. • Its chemistry is dominated by its tendency to lose an electron to form Be2+. As this ion is so small it is highly polarizing, to the extent that its compounds are rather covalent. Its small size means that its complexes tend to be tetrahedral rather than octahedral.
Boron • Boron is a Group 13 element that has properties which are borderline between metals and non-metals (semi metallic). It is a semiconductor rather than a metallic conductor. Chemically it is closer to silicon than to aluminum, gallium, indium, and thallium. • Crystalline boron is inert chemically and is resistant to attack by boiling HF or HCl. When finely divided it is attacked slowly by hot concentrated nitric acid.
Carbon • Carbon is a Group 14 element and is distributed very widely in nature. It is found in abundance in the sun, stars, comets, and atmospheres of most planets. • Carbon is found free in nature in three allotropic forms: amorphous, graphite, and diamond (further details). Graphite is one of the softest known materials while diamond is one of the hardest. Carbon, as microscopic diamonds, is found in some meteorites. Natural diamonds are found in ancient volcanic "pipes" such as found in South Africa. Diamonds are also recovered from the ocean floor off the Cape of Good Hope.
Nitrogen • Nitrogen is a Group 15 element. Nitrogen makes up about 78% of the atmosphere by volume but the atmosphere of Mars contains less than 3% nitrogen. The element seemed so inert that Lavoisier named it azote, meaning "without life". However, its compounds are vital components of foods, fertilizers, and explosives. Nitrogen gas is colorless, odorless, and generally inert. As a liquid it is also colorless and odorless. • When nitrogen is heated, it combines directly with magnesium, lithium, or calcium. When mixed with oxygen and subjected to electric sparks, it forms nitric oxide (NO) and then the dioxide (NO2). When heated under pressure with hydrogen in the presence of a suitable catalyst , ammonia forms (Haber process). Nitrogen is "fixed" from the atmosphere by bacteria in the roots of certain plants such as clover. Hence the usefulness of clover in crop rotation.
Oxygen • Oxygen is a Group 16 element. While about one fifth of the atmosphere is oxygen gas, the atmosphere of Mars contains only about 0.15% oxygen. Oxygen is the third most abundant element found in the sun, and it plays a part in the carbon-nitrogen cycle, one process responsible for stellar energy production. Oxygen in excited states is responsible for the bright red and yellow-green colors of the aurora. About two thirds of the human body, and nine tenths of water, is oxygen. The gas is colorless, odorless, and tasteless. Liquid and solid oxygen are pale blue (see picture above) and strongly paramagnetic (contains unpaired electrons).
Fluorine • Fluorine is a Group 17 element. Fluorine is the most electronegative and reactive of all elements. It is a pale yellow, corrosive gas, which reacts with practically all organic and inorganic substances. Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with a bright flame. It is not uncommon to see fluorine spelled incorrectly as flourine.
Neon • Neon is a very inert element. Neon forms an unstable hydrate. In a vacuum discharge tube, neon glows reddish orange. Of all the rare gases, the discharge of neon is the most intense at ordinary voltages and currents. It is present in the atmosphere as 1 part in 65000. • Liquid neon has over 40 times more refrigerating capacity than liquid helium, and more than 3 times that of liquid hydrogen.
Sodium • Sodium is a Group 1 element (or IA in older labeling styles). Group 1 elements are often referred to as the "alkali metals". The chemistry of sodium is dominated by the +1 ion Na+. Sodium salts impart a characteristic orange/yellow color to flames and orange street lighting is orange because of the presence of sodium in the lamp. • Soap is generally a sodium salt of fatty acids. The importance of common salt to animal nutrition has been recognized since prehistoric times. The most common compound is sodium chloride, (table salt).
Magnesium • Magnesium is a grayish-white, fairly tough metal. Magnesium is the eighth most abundant element in the earth's crust although not found in it's elemental form. It is a Group 2 element (Group IIA in older labeling schemes). Group 2 elements are called alkaline earth metals. Magnesium metal burns with a very bright light. • Magnesium is an important element for plant and animal life. Chlorophylls are porphyries based upon magnesium. The adult human daily requirement of magnesium is about 0.3 g day-1.
Aluminum • Pure aluminum is a silvery-white metal with many desirable characteristics. It is light, nontoxic (as the metal), nonmagnetic and nonsparking. It is somewhat decorative. It is easily formed, machined, and cast. Pure aluminum is soft and lacks strength, but alloys with small amounts of copper, magnesium, silicon, manganese, and other elements have very useful properties. Aluminum is an abundant element in the earth's crust, but it is not found free in nature. The Bayer process is used to refine aluminum from bauxite, an aluminum ore.
Silicon • Silicon is present in the sun and stars and is a principal component of a class of meteorites known as aerolites. Silicon makes up 25.7% of the earth's crust by weight, and is the second most abundant element, exceeded only by oxygen. It is found largely as silicon oxides such as sand (silica), quartz, rock crystal, amethyst, agate, flint, jasper and opal. Silicon is found also in minerals such as asbestos, feldspar, clay and mica. • Silicon is important in plant and animal life. Diatoms in both fresh and salt water extract silica from the water to use as a component of their cell walls. Silicon is an important ingredient in steel. Silicon carbide is one of the most important abrasives. Workers in environments where siliceous dust is breathed may develop a serious lung disease known as silicosis.
Phosphorus • Phosphorus is commonly misspelled "phosphorous". It is an essential component of living systems and is found in nervous tissue, bones and cell protoplasm. Phosphorus exists in several allotropic forms including white (or yellow), red, and black (or violet). White phosphorus has two modifications. Ordinary phosphorus is a waxy white solid. When pure, it is colorless and transparent. It is insoluble in water, but soluble in carbon disulphide. It catches fire spontaneously in air, burning to P4O10, often misnamed as phosphorus pentoxide. When exposed to sunlight, or when heated in its own vapor to 250°C, it is converted to the red variety. This form does not ignite spontaneously and it is a little less dangerous than white phosphorus. The red modification is fairly stable and sublimes with a vapor pressure of 1 atmosphere at 417°C.
Sulphur/Sulfur • Sulphur (sulfur) is a pale yellow, odorless, brittle solid, which is insoluble in water but soluble in carbon disulphide. Sulphur is essential to life. It is a minor constituent of fats, body fluids, and skeletal minerals. • The spelling of sulphur is "sulfur" in the USA while sulphur is common elsewhere. IUPAC has does not have jurisdiction over language but has decided sulfur is preferred. • Sulphur is found in meteorites, volcanoes, hot springs, and as galena, gypsum, Epsom salts, and barite. It is recovered commercially from "salt domes" along the Gulf Coast of the USA. • Jupiter's moon Io owes its colors to various forms of sulphur. A dark area near the crater Aristarchus on the moon may be a sulphur deposit. Carbon disulphide, hydrogen sulphide, and sulphur dioxide should be handled extremely carefully. Hydrogen sulphide in very small concentrations can be metabolized, but in higher concentrations it can cause death quickly by respiratory paralysis. It is insidious in that it quickly deadens the sense of smell. Sulphur dioxide is a dangerous component in atmospheric air pollution and is one of the factors responsible for acid rain.
Chlorine • Chlorine is a greenish yellow gas which combines directly with nearly all elements. Chlorine is a respiratory irritant. The gas irritates the mucous membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odor, and 1000 ppm is likely to be fatal after a few deep breaths. It was used as a war gas in 1915. It is not found in a free state in nature, but is found commonly as NaCl (solid or seawater).
Argon • Argon is a colorless and odorless gas present to a very small extent in the atmosphere. Argon is very inert (indeed it is referred to as one of the noble gases) and is not known to form true chemical compounds. It makes a good atmosphere for working with air-sensitive materials since it is heavier than air and less reactive than N2. Today, the chemical symbol for argon is Ar but until 1957 its symbol was simply A.
Potassium • Potassium is a metal and is the seventh most abundant and makes up about 1.5 % by weight of the earth's crust. Potassium is an essential constituent for plant growth and it is found in most soils. It is also a vital element in the human diet. • Potassium is never found free in nature, but is obtained by electrolysis of the chloride or hydroxide, much in the same manner as prepared by Davy. It is one of the most reactive and electropositive of metals and, apart from lithium, it is the least dense known metal. It is soft and easily cut with a knife. It is silvery in appearance immediately after a fresh surface is exposed. • It oxidizes very rapidly in air and must be stored under argon or under a suitable mineral oil. As do all the other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It usually catches fire during the reaction with water. Potassium and its salts impart a lilac color to flames.
Calcium • Calcium as the element is a grey silvery metal. The metal is rather hard. Calcium is an essential constituent of leaves, bones, teeth, and shells. Calcium is the fifth most abundant element in the earth's crust and makes up more than 3% of the crust. Calcium does not occur as the metal itself in nature and instead is found in various minerals including as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate (CaCO3). Calcium carbonate is the basis of the cement industry. • Calcium is classified chemically as one of the alkaline earth elements (that is, in Group 2 of the periodic table. The metal is rather reactive. It readily forms a white coating of calcium nitride (Ca3N2) in air. It reacts with water and the metal burns with a yellow-red flame, forming largely the nitride.
Scandium • Scandium is a silvery-white metal which develops a slightly yellowish or pinkish cast upon exposure to air. It is relatively soft, and resembles yttrium and the rare-earth metals more than it resembles aluminum or titanium. Scandium reacts rapidly with many acids. • Scandium is apparently a much more abundant element in the sun and certain stars than on earth.
Titanium • Titanium s a lustrous, white metal when pure. Titanium minerals are quite common. The metal has a low density, good strength, is easily fabricated, and has excellent corrosion resistance. The metal burns in air and is the only element that burns in nitrogen. It is marvelous in fireworks. • Titanium is resistant to dilute sulphuric and hydrochloric acid, most organic acids, damp chlorine gas, and chloride solutions. Titanium metal is considered to be physiologically inert. • Titanium is present in meteorites and in the sun. Some lunar rocks contain high concentrations of the dioxide, TiO2. Titanium oxide bands are prominent in the spectra of M-type stars.
Vanadium • Pure vanadium is a greyish silvery metal, and is soft and ductile. It has good corrosion resistance to alkalis, sulphuric acid, hydrochloric acid, and salt waters. The metal oxidizes readily above 660°C to form V2O5. Industrially, most vanadium produced is used as an additive to improve steels.
Chromium • Chromium is steel-gray, lustrous, hard, metallic, and takes a high polish. Its compounds are toxic. It is found as chromite ore. Siberian red lead (crocoite, PrCrO4) is a chromium ore prized as a red pigment for oil paints. • Emerald is a form of beryl (a beryllium aluminum silicate) which is green because of the inclusion of a little chromium into the beryl crystal lattice in place of some of the aluminum ions. Similarly, traces of chromium incorporated into the crystal lattice of corundum (crystalline aluminum oxide, Al2O3) as a replacement for some of the Al3+ ions results in another highly colored gem stone, in this case the red ruby.
Manganese Manganese metal is gray-white, resembling iron, but is harder and very brittle. The metal is reactive chemically, and decomposes cold water slowly. Manganese is widely distributed throughout the animal kingdom. It is an important trace element and may be essential for utilization of vitamin B. Manganese is present in quantity the floor of oceans. It is an important component of steel.
