Since calcium forms such hard minerals, it is useful in building materials, such as plaster, mortar, and cement. Mortar is made from calcium oxide, CaO, also known as lime, or quicklime. When calcium oxide is treated with water it forms calcium hydroxide, Ca OH 2 , or slaked lime, which absorbs carbon dioxide from the air and gradually forms calcium carbonate, CaCO 3.
Lime, heated by hydrogen burning in oxygen, burns with a brilliant white light, which can be focused into a narrow beam visible over great distances. This kind of lighting was used in lighthouses, in surveying, and in theaters to produce spotlights leaving the actor "in the limelight".
Calcium chloride is a deliquescent it absorbs enough water from the air that it dissolves in the solution , and is used to remove moisture from the air in damp basements. It would take a stronger person that me to resist calling a freshly opened box of calcium chloride that wasn't behaving properly as a "juvenile deliquescent.
Strontium is a shiny, relatively soft metal. The name of the element is derived from Strontian, a town in Scotland where the mineral strontianite was discovered, from which strontium was first isolated. It is found in the Earth's crust at a concentration of ppm, making it the 16th most abundant element.
Strontium salts produce brilliant red colors when heated, and are used in fireworks and flares for this reason. Radioactive strontium a beta-emitter is produced in nuclear explosions; since it is chemically similar to calcium, it becomes incorporated into bone in people who are exposed to it. Strontium is a beta-emitter, and interferes with the production of red blood cells. Barium is a shiny, soft metal. The name of the element is derived from the Greek word barys , which means "heavy," in reference to the high density of some barium minerals.
It is found in the Earth's crust at a concentration of ppm, making it the 14th most abundant element. Barium was discovered in the s in the form of the "Bologna stones" now known to be barium sulfate, BaSO 4 discovered near Bologna, Italy. These stones glowed in the presence of light, and also when heated. Barium salts give off a green color when heated, and are used in fireworks in the form of barium nitrate, Ba NO 3 2.
Barium sulfate, BaSO 4 , is poisonous, but it is so insoluble that that it passes through the body before any absorption of barium can take place. It is used in the diagnosis of some intestinal problems in the form of "barium enemas": barium sulfate is opaque to X-rays, and can be used to take X-rays of the digestive tract.
Radium is a soft, shiny, radioactive metal. The name of the element was derived from the Latin word for "ray," radius , because of its ability to glow in the dark with a faint blue light. Heat plus hydrogen in an oxygen atmosphere is, of course, a very dangerous combination! The reaction becomes more vigorous as one moves from top to bottom in Group 1A: lithium sizzles fiercely in water, a small amount of sodium reacts even more vigorously, and even a small amount of potassium metal reacts violently and usually ignites the hydrogen gas; rubidium and cesium explode.
This is a result of the fact that the size of the element increases as we move down the group: as the size of the metal increases, the valence electron is farther away from the nucleus, and is thus more easily removed i. Although hydrogen is placed at the top of Group 1A in most versions of the periodic table, it is very different from the other members of the alkali metal group. In its elemental form, hydrogen is a colorless, odorless, extremely flammable gas at room temperature, consisting of diatomic molecules of H 2.
Under tremendous pressure about 2 million atmospheres , it can be converted to a metallic form, capable of conducting electricity. It has been theorized that center of the planet Jupiter consists of metallic hydrogen. In the Earth's crust, it is found at a concentration of ppm mostly in the form water and of organic compounds , making it the 10th most abundant element.
Of course, there's also "dark matter" and "dark energy" to worry about, but that's another story. Hydrogen, helium, and trace amounts of lithium were produced at the beginning of the Universe in the Big Bang, and became concentrated into stars by the force of gravity.
The fusion of hydrogen and its isotopes see below also powers the hydrogen bomb, which contains lithium deuteride LiD and tritium; the explosion of a fission-powered bomb produces neutrons which initiate fusion of the deuterium with the tritium, releasing vast amounts of energy. Research into achieving controlled nuclear fusion to generate electricity is being conducted, but the extremely high temperatures that are necessary to initiate the fusion reactions present a major challenge to physicists.
Hydrogen typically does not form cations, but instead forms compounds through covalent bonding. Hydrogen can form bonds to many other elements, such as nitrogen NH 3 and its derivatives , oxygen H 2 O and sulfur H 2 S , the halogens HX , and carbon, where it is found in millions of different hydrocarbons and other organic molecules almost all organic molecules contain at least some hydrogen atoms. Hydrogen can also bond to metal atoms, such as lithium LiH , calcium CaH 2 , etc.
In these compounds, the bonding is usually pictured as a metal cation combined with a hydride anion H -. On some periodic tables, in fact, hydrogen is placed at the top of Group 7A, since like the halogens, it can form a -1 charge. Hydrogen is also found in acids , which are molecules containing easily-removed hydrogen atoms, usually connected to oxygen, nitrogen, or a halogen. This is a greatly oversimplified explanation of acid-base chemistry. Hydrogen was discovered by the English chemist Henry Cavendish in ; hydrogen had been observed before, but Cavendish was the first to recognize not only that it was an element, but that it burned to form water, which also provided conclusive proof that water was not itself an element.
The name "hydrogen" was derived by the French chemist Antoine Lavoisier from the Greek words hydro "water" and genes "forming".
There are three isotopes of hydrogen. Hydrogen-1, or protium , contains one proton in its nucleus, and is by far the most common form of hydrogen Hydrogen-2, or deuterium , contains one proton and one neutron in its nucleus, and comprises the remaining 0.
Hydrogen-3, or tritium , contains one proton and two neutrons, and is only found in trace amounts; it is produced by the interaction of cosmic rays on gases in the upper atmosphere, and in nuclear explosions, but since it has a half life of only Heavy water is water made from two atoms of deuterium and one atom of oxygen.
This form of water is literally heavier than "ordinary" water, since an atom of deuterium is twice as heavy as an atom of "regular" hydrogen. H 2 O has a molar mass of Ordinary water contains about 1 molecule of D 2 O for every molecules of H 2 O. The electrolysis of water concentrates D 2 O in the solution, since the lighter isotope evaporates from the solution slightly faster.
Successive electrolysis experiments allow pure heavy water to be produced, but it takes about , gallons of water to produce 1 gallon of heavy water by this method. Heavy water is used as a moderator in nuclear reactions: it slows down fast-moving neutrons, allowing them to be captured more easily by other nuclei. The generation of heavy water was important during the research on nuclear fission that went into the Manhattan Project during World War II. For a typical person, a fatal dose would require drinking nothing but heavy water for 10 to 14 days, so it's pretty doubtful that heavy water poisoning will be featured on CSI anytime soon.
Most hydrogen is prepared industrially be reacting coal or hydrocarbons with steam at high temperatures to produce carbon monoxide and hydrogen gas a mixture of carbon monoxide and hydrogen is called synthesis gas , and can be used in manufacturing methanol. On smaller scales it can be produced by the reaction of active metals such as zinc, calcium, etc.
Hydrogen gas is combined with nitrogen in the Haber process to synthesize ammonia NH 3 , which is widely used in fertilizers. It is also used in the manufacture of hydrogenated vegetable oils; in this reaction, hydrogen atoms add to the carbon-carbon double bonds in the vegetable oils double-bonded carbons bond to fewer hydrogen atoms than single-bonded carbons — i. Another use for hydrogen is in rocket fuels: the Saturn V rockets that launched the Apollo lunar missions used , gallons of kerosene and , gallons of liquid oxygen in its first stage S-IC , , gallons of liquid hydrogen and 83, gallons of liquid oxygen in its second stage S-II , and 69, gallons of liquid hydrogen and 20, gallons of liquid oxygen in its third S-IVB stage; the Space Shuttle main engines use , gallons of liquid hydrogen and , gallons of liquid oxygen.
Hydrogen is lighter than air, and was used in balloons and dirigibles also known as airships or zeppelins. Dirigibles were used in city-to-city air travel in the early s, and in trans-Atlantic crossings in the s and s.
During World War I, German zeppelins were used in bombing runs over England, since they could fly higher than the British planes. On May 6, , the German dirigible Hindenburg caught fire as it came in for a landing at Lakehurst Naval Air Station in New Jersey; 35 people out of the 97 aboard and one person on the ground were killed. The exact cause of the fire is still the subject of speculation, but the disaster signaled the beginning of the end for airship travel.
Modern "blimps" use helium to provide lift, which avoids the problem of hydrogen's flammability. Molecules which contain hydrogen bonded to nitrogen, oxygen, or fluorine can attract one another through the formation of hydrogen bonds. Hydrogen bonds are a particularly strong form of dipole-dipole forces , which arise because of the unequal sharing of electrons in some covalent bonds.
If one atom in a covalent bond is more electronegative than the other, it "pulls" harder on the electrons that the two atoms share, giving the more electronegative atom a partial negative charge, and the less electronegative atom a partial positive charge. The partially negative atom on one molecule attracts the partially positive atom on a neighboring molecule, causing the two molecules to be more attracted to each other than two nonpolar molecules which have no electronegativity differences between their bonded atoms would be.
Molecules that interact by these dipole-dipole forces tend to have higher boiling points than nonpolar molecules, because higher temperatures are necessary to overcome the attractive forces between the molecules and separate the molecules into the gas phase. In the case of O—H, N—H, and F—H bonds, the electronegativity differences are particularly large because fluorine, oxygen, and nitrogen are the most strongly electronegative elements. The attractive forces between molecules containing these bonds are particularly strong, and are given the name hydrogen bonds.
Hydrogen bonds are not as strong as covalent bonds, but they greatly influence the physical properties of many substances. This creates a layer over the surface of the metal. The alkali metals react with water to produce a metal hydroxide and hydrogen. For example, sodium reacts with water:. Sodium hydroxide is an alkali. It is a base that dissolves in water to form an alkaline solution. This solution:.
Write the word equation and balanced chemical equation for the reaction of potassium with water. The table shows the main observations when lithium, sodium and potassium are added to water. These observations may be used to find a pattern in the reactivity of the group 1 elements. These observations show that the reactivity of these metals increases going down the group. Rubidium is placed below potassium in group 1.
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