The period 2 element is one of the chemical elements in the second row (or period) of the periodic table of chemical elements. Periodic tables are arranged in rows to represent repetitive (periodic) trends in chemical behavior of elements as their atomic numbers increase; a new line begins when the behavior of chemistry starts to recur, creating an element column with a similar property.
The second period contains elements of lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. This situation can be explained by modern theories of atomic structure. In the quantum mechanical description of the atomic structure, this period corresponds to the filling of the 2s and 2p orbital. The 2 period elements obey the octet rules because they require eight electrons to complement their valence shells. The maximum number of electrons that can be accommodated by these elements is ten, two in a 1s orbital, two in a 2s orbital, and six in a 2p orbital.
Video Period 2 element
Tren periodik
Period 2 is the first period in the periodic table that can be drawn from the periodic trend. Period 1, which contains only two elements (hydrogen and helium) is too small to draw a conclusive trend out of it, especially since the two elements do not behave the same as other s-block elements. Period 2 has a much more conclusive trend. For all elements in period 2, when the atomic number increases, the radius of the atomic elements decreases, electronegativity increases, and the ionization energy increases.
Period 2 has only two metals (lithium and beryllium), making it the least metalic period (period 1 has no metal, but as mentioned above, has only two elements, so it is impossible to have more metals) and the most non- metal, with four. The elements in period 2 often have the most extreme properties in each group; for example, fluorine is the most reactive halogen, neon is the most inert noble gas, and lithium is the least reactive alkali metal.
All elements of period 2 completely obey the rules of Madelung; in period 2, lithium and beryllium fill 2s subshell, and boron, carbon, nitrogen, oxygen, fluorine, and neon fill 2p subpellites. Periods share these properties with periods 1 and 3, none of which contain transitional elements or inner transition elements, which are often different from rules.
Lithium
Lithium (Li) is an alkali metal with atomic number 3, occurs naturally in two isotopes: 6 Li and 7 Li. Both form all the natural occurrences of lithium on Earth, although further isotopes have been synthesized. In ionic compounds, lithium loses electrons into positively charged, forming Li cations. Lithium is the first alkali metal in the periodic table, and the first metal is in any form in the periodic table. At standard temperature and pressure, lithium is a soft, silver-white, highly reactive metal. With a density of 0.564 g  · cm -3 , lithium is the lightest metal and the most solid solid element.
Lithium is one of several elements synthesized in the Big Bang, making it a primordial element. Lithium is the 33rd most abundant element on earth, occurring in concentrations between 20 and 70 ppm by weight, but because its high reactivity is only found naturally in the compound.
Lithium salts are used in the pharmacology industry as a mood stabilizer. They are used in the treatment of bipolar disorder, where they have a role in treating depression and mania and can reduce the likelihood of suicide. The most commonly used compounds are lithium carbonate, Li 2 CO 3 , lithium lithium, Li 3 C 6 H 5 O 7 , lithium sulfate, Li 2 SO 4 , and lithium orotate, LiC 5 2 O
Beryllium (Be) is a chemical element with an atomic number 4, occurring in the form of 9 Be. At standard temperature and pressure, beryllium is a strong alkaline earth metal, colored in gray, light, brittle, bivalent steel, with a density of 1.85 g  ± cm -3 . It also has one of the highest melting points of all light metals. The most common isotope of Beryllium is 9 Be, which contains 4 protons and 5 neutrons. It makes up nearly 100% of all natural beryllium and the only stable isotope; Yet another isotope has been synthesized. In ionic compounds, beryllium loses two valence electrons to form a cation, Be 2 .
A small amount of beryllium is synthesized during the Big Bang, although most decays or reacts further to create larger nuclei, such as carbon, nitrogen or oxygen. Beryllium is a component of 100 of 4000 known minerals, such as bertrandit, Be 4 Si 2 O 7 (OH) 2 , beryl, Al 3 Be 6 O 18 , chrysoberyl, Al 2 BeO 4 , and phenakite, Be 2 SiO 4 . Beryl valuable shapes are aquamarine, red beryl and emerald. The most commonly used sources of beryllium are beryl and bertrandite and the production involves the reduction of beryllium fluoride with magnesium metal or electrolysis of liquid beryllium chloride, which contains some sodium chloride such as beryllium chloride is a poor conductor of electricity.
Due to its rigidity, its light weight, and dimensional stability over a wide temperature range, beryllium metal is used as a structural material in aircraft, missiles, and communications satellites. It is used as an alloying agent in beryllium copper, which is used to make electrical components due to high electrical and thermal conductivity. The beryllium sheets are used in X-ray detectors to filter visible light and only let X-rays penetrate. It is used as a neutron moderator in nuclear reactors because the light nuclei are more effective at slowing the neutrons than the heavy nuclei. Low weight and high stiffness Beryllium also makes it useful in the construction of tweeters in loudspeakers.
Beryllium and beryllium compounds are classified by the International Agency for Cancer Research as group 1 carcinogen; they are carcinogenic in both animals and humans. Chronic berylosis is a systemic and pulmonary granulomatous disease caused by beryllium exposure. Between 1% - 15% of people are sensitive to beryllium and may develop an inflammatory reaction in their respiratory and skin system, called chronic beryllium or berylliotic disease. The immune system recognizes beryllium as foreign particles and mounts attacks against them, usually in the lungs where they are inhaled. It can cause fever, fatigue, weakness, night sweats and difficulty breathing.
Boron
Boron (B) is a chemical element with atomic number 5, occurs as 10 B and 11 B. At standard temperature and pressure, boron is a trivalent metalloid that has several different allotropes. Amorphous boron is a brown powder that forms as the product of many chemical reactions. Boron crystals are a very hard black material with a high melting point and exist in many polymorphs: Two rhombohedral forms ,? -boron and? -borons contain 12 and 106.7 atoms in the cells of each rhombohedral unit, and 50-atom tetragonal boron is the most common. Boron has a density of 2.34 -3 . The most common islet of Boron is 11 B at 80.22%, which contains 5 protons and 6 neutrons. Another common isotope is 10 at 19.78%, which contains 5 protons and 5 neutrons. It is the only stable isotope of boron; Yet another isotope has been synthesized. Boron forms covalent bonds with other non-metals and has oxidation states of 1, 2, 3, and 4. Boron does not occur naturally as a free element, but in compounds such as borate. The most common boron source is tourmaline, borax, Na 2 4 O 5 (OH) 4 Â · 8H 2 O, and kernite, Na 2 < 4 O 5 (OH) 4 Ã, Â · 2H 2 O. difficult to get pure boron. This can be done through the reduction of magnesium boron trioxide, B 2 O 3 . This oxide is made by melting boric acid, B (OH) 3 , which in turn is obtained from borax. A small amount of pure boron can be prepared by thermal decomposition of boron bromide, BBr 3 , in a hydrogen gas over hot tantalum wire, which acts as a catalyst. The most commercially important sources of boron are: sodium tetraborate pentahydrate, Na 2 B 4 < 2 Ã, Â · 5H 2 O, which is used in large quantities in the manufacture of fiberglass bleaching insulation and sodium perborate; boron carbide, ceramic materials, used to make protective material, especially in bulletproof vests for soldiers and police; orthoboric acid, H 3 BO 3 or boric acid, used in the production of fiberglass textiles and flat panel displays; sodium tetraborate decahydrate, Na 2 B 4 O 7 Ã, Â · 10H 2 O or borax, used in adhesive production; and boron-10 isotopes are used as controls for nuclear reactors, as a shield for nuclear radiation, and in instruments used to detect neutrons.
Boron is an important plant micronutrient, necessary for strength and development of cell walls, cell division, seed and fruit development, sugar transport and hormone development. However, high soil concentrations of more than 1.0 ppm may cause leaf necrosis and poor growth. Levels as low as 0.8 ppm can cause these symptoms to appear in plants, especially boron-sensitive. Most plants, even those tolerant to boron in the soil, will exhibit symptoms of boron toxicity when boron levels are higher than 1.8 ppm. In animals, boron is an ultratrace element; in human food, the daily intake ranges from 2.1 to 4.3 mg boron/kg body weight (bw)/day. It is also used as a supplement for the prevention and treatment of osteoporosis and arthritis.
Carbon
Carbon is a chemical element with an atomic number 6, occurs as 12 C, 13 C and 14 C. At standard temperature and pressure, carbon is solid , occurs in many different allotropes, the most common being graphite, diamond, fullerene and amorphous carbon. Graphite is a soft, opaque hexagonal crystalline with excellent conductive and thermodynamic properties. But diamonds are highly transparent colorless cubic crystals with poor conductive properties, are the hardest known natural minerals and have the highest refractive index of all gems. In contrast to the lattice structure of diamond and graphite crystals, fullerenes is a molecule, named after Richard Buckminster Fuller whose architecture resembles a molecule. There are several different fullerenes, the best known being "buckeyball" C 60 . Little is known about fullerenes and they are the subject of current research. There is also an amorphous carbon, ie carbon without a crystal structure. In mineralogy, this term is used to refer to soot and coal, although this is not really amorphous because it contains small amounts of graphite or diamond. The most common carbon isotope at 98.9% is 12 C, with six protons and six neutrons. 13 C is also stable, with six protons and seven neutrons, at 1.1%. The number of traces of 14 C also occurs naturally but this isotope is radioactive and decays with a half-life of 5730 years; used for radiocarbon dating. Other carbon isotopes have also been synthesized. Carbon forms covalent bonds with other non-metals with oxidation states -4, -2, 2 or 4.
Carbon is the fourth most massive element in the universe by mass after hydrogen, helium and oxygen and is the second most abundant element in the human body by mass after oxygen, the third most by the number of atoms. There are an almost unlimited number of compounds containing carbon because of the carbon's ability to form long and stable C-C bond chains. The simplest carbon-containing molecule is a hydrocarbon, which contains both carbon and hydrogen, although it sometimes contains other elements in the functional group. Hydrocarbons are used as fossil fuels and to produce plastics and petrochemicals. All organic compounds, which are essential for life, contain at least one carbon atom. When combined with oxygen and hydrogen, carbon can form many groups of important biological compounds including sugar, lignans, chitin, alcohols, fats, and aromatic, carotenoid and terpene esters. With nitrogen to form alkaloids, and with the addition of sulfur also forms antibiotics, amino acids, and rubber products. With the addition of phosphorus to these other elements, it forms DNA and RNA, the chemical code of life, and adenosine triphosphate (ATP), the most important energy transfer molecule in all living cells.
Nitrogen
Nitrogen is a chemical element with atomic number 7, symbols N and atomic mass 14,00674 u. The elemental nitrogen is a diatomic gas that is colorless, odorless, tasteless, and mostly inert under standard conditions, which make up 78.08% of Earth's atmospheric volume. The nitrogen element was discovered as a separable air component, by Scottish physician Daniel Rutherford, in 1772. It occurs naturally in the form of two isotopes: nitrogen-14 and nitrogen-15.
Many important industrial compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. A very strong bond in the nitrogen element dominates nitrogen chemistry, causing difficulties for organisms and industries to break bonds to change N
2 molecules into useful compounds, but at the same time cause the release of large amounts of energy that are often useful when compounds burn, explode, or rot. back into nitrogen gas.
Nitrogen occurs in all living organisms, and the nitrogen cycle describes the movement of elements from air into the biosphere and organic compounds, then back into the atmosphere. Synthetically produced nitrates are the main ingredients of industrial fertilizers, and also key pollutants that cause eutrophication of water systems. Nitrogen is the constituent element of amino acids and thus proteins, and nucleic acids (DNA and RNA). It is in the chemical structure of almost all neurotransmitters, and is a decisive component of alkaloids, biological molecules produced by many organisms.
Oxygen
Oxygen is a chemical element with an atomic number of 8, occurs mostly as 16 O, but also 17 O and 18 O.
Oxygen is the third most common element by mass in the universe (although carbon makes up more of it is lighter atom). It's highly electronegative and non-metallic, usually diatomic, gas to very low temperatures. Only fluorine is more reactive among non-metallic elements. These are two short electrons of a full octet and easily take electrons from other elements. It reacts violently with alkali metals and white phosphorus at room temperature and is less coarse with alkaline earth metals heavier than magnesium. At higher temperatures it burns most other metals and many non-metals (including hydrogen, carbon, and sulfur). Many oxides are highly stable substances that are difficult to decipher - such as water, carbon dioxide, alumina, silica, and iron oxide (the latter often appear as rust). Oxygen is part of the most appropriate substance described as some metallic salts and oxygen-containing acids (thus nitrates, sulfates, phosphates, silicates, and carbonates.
Oxygen is essential for all life. Plants and phytoplankton photosynthesize water and carbon dioxide and water, both oxides, in the presence of sunlight to form sugars with the release of oxygen. Sugar then turns into substances such as cellulose and (with nitrogen and often sulfur) proteins and other vital substances from life. Animals mainly but also fungi and bacteria ultimately rely on photosynthesis of plants and phytoplankton for food and oxygen.
Fire uses oxygen to oxidize compounds normally from carbon and hydrogen to water and carbon dioxide (though other elements may be involved) either in uncontrolled fires that destroy buildings and woods or fire controlled in machinery or that supply electrical energy from turbine, heat to keep the building warm, or motive force that drives the vehicle.
Oxygen makes up about 21% of Earth's atmosphere; all this oxygen is the result of photosynthesis. Pure oxygen has been used in the medical care of people who have difficulty breathing. Excess oxygen is toxic.
Oxygen is initially associated with acid formation - until some acids are shown to have no oxygen in them. Oxygen is named for the formation of acids, especially with non-metals. Some oxides of some non-metals are highly acidic, such as sulfur trioxide, which form sulfuric acid when in contact with water. Most of the oxides with metals are alkaline, some very like potassium oxide. Some of the metal oxides are amphoteric, such as aluminum oxide, which means that they can react with acids and bases.
Although oxygen is usually a diatomic gas, oxygen can form allotropes known as ozone. Ozone is a triathomic gas that is even more reactive than oxygen. Unlike ordinary diatomic oxygen, ozone is a toxic substance that is generally regarded as a pollutant. In the upper atmosphere, some oxygen forms ozone that has the properties of absorbing harmful ultraviolet rays within the ozone layer. Land life is not possible before the formation of the ozone layer.
Fluorine
Fluor is a chemical element with atomic number 9. It occurs naturally in the only stable form 19 F.
Fluor is pale yellow diatomic gas under normal conditions and drops to very low temperatures. Short of one electron from a very stable octet in each atom, fluorine molecules are quite unstable so they break easily, with fluorine atoms that tend to take single electrons from almost any other element. Fluorine is the most reactive of all elements and even attacks many oxides to replace oxygen with fluorine. Fluor even attacks silica, one of the preferred ingredients for transporting strong acids, and burning asbestos. It attacks the common salt, one of the most stable compounds, with the release of chlorine. It never appears in nature and almost never remains united for long. It burns hydrogen simultaneously if liquids or gases - even at temperatures near absolute zero. It is very difficult to isolate from any compound, let alone stay unincorporated.
Fluorine gas is a very dangerous material because it attacks almost all organic materials, including live meat. Many of the binary compounds that are formed (called fluorides) themselves are highly toxic, including soluble fluorides and especially hydrogen fluoride. But fluorine forms a very strong bond with many elements. With sulfur can form highly stable sulfafets and chemically inert sulfafluoride; with carbon can form an extraordinary material Teflon which is a stable and non-flammable solid with high melting point and very low friction coefficient which makes it an excellent coating for cooking pots and raincoats. The fluorine-carbon compound includes some unique plastics. it is also used as a reactant in the manufacture of toothpaste.
Neon
Neon is a chemical element with atomic number 10, occurs as 20 Ne, 21 Ne and 22 Ne.
Neon is a monoatomic gas. With a complete octet the outer electrons are very resistant to the removal of any electrons, and can not accept electrons from anything. Neon has no tendency to form normal compounds under normal temperature and pressure; it is effectively inert. This is one of the so-called "noble gases".
Neon is an atmospheric trace component with no biological role.
Maps Period 2 element
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