Elements

Elements

 

•

Nitrogen

Origin

Nitrogen (Latin nitrum-iy this νίτρον Greek, "nitro"-name that has historically been used to refer vaguely to various compounds of sodium and potassium containing nitrogen-, y-gen, from the Greek root γεν -, "generate") is formally considered to have been discovered by Daniel Rutherford in 1772 when it releases some of its properties. However, at the same time is also devoted to his study he isolated Scheele, Cavendish, and Priestley.

Nitrogen is an inert gas that Lavoisier referred to it as a whip (azotes) meaning without life1 (or perhaps named it for not being fit for respirar2). It ranked among the permanent gases, especially since I did not get to see Faraday liquid at 50 atm and -110 ° C until experiments Cailletet Pictet in 1877 and got liquefy.

Nitrogen compounds were known in the Middle Ages, thus the alchemists called aqua forties nitric acid and aqua regain (royal water) to the mixture of nitric acid and hydrochloric acid, known for its ability to dissolve gold.

Obtaining

Nitrogen is the major component of the Earth's atmosphere (78.1% volume) and for industrial use is obtained from the distillation of liquid air. Is also present in the remains of animals, such as guano, usually in the form deurea, uric acid and both compounds.

He also holds 3% of the elemental composition of the human body. Have been observed nitrogen-containing compounds in outer space and the isotope nitrogen-14 is created in nuclear fusion processes of stars.

Reactions

With hydrogen as ammonia (NH3), hydrazine (N2H4) and hydrogen aside (N3H, also known as hydrogen aside or hydrazoic acid). Liquid ammonia, amphoteric as water, acts as a base in an aqueous solution to form ammonium ions (NH4 +), and behaves as an acid in the absence of water, giving a proton to a base and leading to amide anion (NH2 ). Also known long chains and cyclic nitrogen compounds, but are very unstable.

With the halogens form: NF3, NF2Cl, NFCl2, NCl3, NBr3.6 NH3, NH3 NI3.6, N2F4, N2F2 (cis and Trans), N3F, N3Cl, N3Br and N3I.

With oxygen it forms several oxides have already named: the nitrous or laughing gas, nitric acid and nitrogen dioxide. Are the products of combustion processes contributing to the onset of photo smog episodes chemical contaminants. Other oxides are dinitrogen trioxide (N2O3) and dinitrogen pentoxide (N2O5), both very unstable and explosive.

 

Applications

The most important commercial application is diatomic nitrogen from ammonia production by the Haber process. Ammonia is used subsequently in the manufacture of fertilizers and nitric acid.

Nitric acid salts include important compounds such as potassium nitrate (nitro or nitrate used in the manufacture of powder) and ammonium nitrate fertilizer.

Organic nitrogen compounds such as nitroglycerin and trinitrotoluene are often explosive. Hydrazine and its derivatives are used as a rocket fuel.

The cycle of this element is more complex than the carbon, as is present in the atmosphere not only as N2 (78%) but also in a wide variety of compounds. It can be found mainly as N2O, NO and NO2, NOx called. Also other combinations with oxygen forms such as N2O3 and N2O5 (anhydrides), "precursors" of nitrous and nitric acids. With hydrogen as ammonia (NH3) gas compound under normal conditions.

Uses

Nitrogen is a colorless, odorless, tasteless and generally inert (non-reactive). If you've ever wondered what it is nitrogen, then have a list of possible uses:

•

Nitrogen is used to preserve food by stopping oxidation packaged food that causes spoilage.

•

The bulbs may contain nitrogen as a cheaper alternative to argon.

•

Nitrogen gas is often used on top of liquid explosives are detonated to prevent.

•

Nitrogen is used to produce many electrical components such as transistors, diodes and integrated circuits.

•

When dried and pressurized, the nitrogen gas is used as a dielectric gas for high voltage equipment.

•

It is used to manufacture stainless steel.

•

Used to reduce the risk of fire in military systems of the aircraft fuel.

Physical Properties

Atomic number 7

Atomic weight: 14,008

Covalent atomic radius 0.70 A

N3-ion radius of 1.71 A

Abundance of the isotopes: N14, 99.62%; N15, 0.38%

Spectral notation: 1s2, 2s2, 2p3

 

Form: Colorless, odorless and tasteless.

Molecular formula: N2

Absolute density (in c. N.). 1.2506 g / L

Relative density (air = I), 0.9672

Density of liquid N2, 8,808

Solubility in water (cm3 in c. N. Per liter):

At 0 ° C. ...... 23.54

At 25 ° C. .... 14.34

Boiling point -195.8 ° C

Freezing point, -209.86 ° C

Critical temperature, -147.1 ° C

Critical pressure, 33.5 atm.

 

Chemical Properties

The heat of dissociation of the nitrogen molecules is -171.14 kcal per mole of N2 (absorbed heat), being greater than that of any other diatomic molecule. A 3500 ° C only 5% of the nitrogen molecules are dissociated to atoms. Consequently, nitrogen is the most idle, except inert gases. The structure of the molecule,: N ::: N:, with three pairs of shared electrons, explains the chemical inertness of nitrogen. However, when heated to high temperature is combined with certain metals to form nitrides with them and in this way are easily obtained, NLi3, N2Ca3, N2Mg3 and NB; nitrides active metals are ionic and contain the nitride ion-N3. Also reacts with non-metallic elements such as oxygen and hydrogen.

 

Isotopes

There are two stable isotopes of nitrogen, N-14 and N-15, the first, which occurs in the carbon-nitrogen cycle of the stars, the most common undoubtedly (99.634%). Ten isotopes have been synthesized, one has a semi disintegration period nine minutes (N-13) and the rest of seconds or less.

Biological reactions of nitrification and gentrification have a determining influence on the dynamics of nitrogen in the soil, often producing an N-15 enrichment of the substrate.

 Phosphorus

Origin

The phosphorus-phosphorus Latin and Greek this φωσφόρος, light-bearer former name of the planet Venus, was discovered by German alchemist Henning Brandt in 1669 in Hamburg by distilling a mixture of urine and sand (used 50 cubes) while searching the philosopher's stone; urea obtained by evaporating a white material that glowed in the dark and burned like a bright flame, and since then, substances that glow in the dark without burning are called phosphors. Brandt, the first known person who has discovered a chemical element, kept his discovery secret, but another German alchemist, Kunckel, rediscovered it in 1677 and taught how to spend Boyle.

Phosphorus is found naturally in rocks and soil ground, and is released into the soil by erosion.

In nature, the availability of phosphorus is produced by the decomposition of rocks, which contain phosphates, and by natural erosion reach soils and waters (rivers, lakes and seas). In volcanic areas, past or present, the phosphorus compounds are deposited by ash. Therefore volcanic soils rich in phosphorus compounds.

Phosphorous is introduced into the cycle as phosphate ion (PO4-3). The phosphates are washed during the weathering of the bedrock, and then being available to plants are either extracted from the mining operations. Many phosphates are poorly soluble and are removed by sedimentation cycle. The largest phosphorus reserves in the world are in the rock called phosphorite. As this rock is broken down by the hydrological cycle, washed large amounts of phosphate into coastal waters, while a part remains in the soil.

The largest reservoir of phosphorus is in the crust and deposition of marine rocks.

Obtaining

Because of its reactivity, phosphorus is not found native in nature, but part of numerous minerals. Apatite is an important source of phosphorus, significant deposits exist in Morocco, Russia, USA. UU. and other countries.

The white allotrope can be obtained by various methods, in one of them, tricalcium phosphate, obtained from rocks, is heated in a furnace at 1450 ° C in the presence of silica and carbon reducing phosphorus released in vapor form.

 

 

Reactions

Phosphorus combines readily with oxygen to form oxides, the most important being the oxide of phosphorus (III), P2O3, and phosphorus oxide (V), P2O5. Phosphorus oxide a white crystalline solid, is used as reducing agent. Is a deliquescent substance (dissolved with humidity) and its vapor is toxic. The phosphorus oxide (V), an amorphous solid, white deliquescent sublimates at 250 ° C. Reacts with water to form phosphoric acid and is used as a drying agent. Phosphorus form hydrides with hydrogen, the most important being the PH3, similar to ammonia (NH3) and nitrogen hydride. All halogens are combined directly with phosphorus halides forming, which are used in the preparation of hydrogen halides and organic compounds. Phosphorus compounds most important commercial are phosphoric acid and its salts known as phosphates. Most of the phosphorus compounds are used as fertilizers. They are also used to clarify sugar solutions, as well as evidence of silk fabrics and fireproof materials, and phosphor-bronze alloys, copper and phosphorus. White phosphorus is used to make red phosphorus rodenticides to make matches or matches.

Applications

Most of phosphoric acid (85%) is used in the manufacture of fertilizers. Phosphorus, along with nitrogen and potassium are essential elements for plants. Other uses of phosphoric acid include its applications in food industry, is used in the preparation of yeast and instant cereals in the manufacture of cheese, for curing hams and making bitter refreshments. Is also used to treat metals making them more resistant to corrosion.

Uses

Phosphorus is used as fertilizer, is also used to clarify sugar solutions, as well as evidence of silk fabrics and materials ignofugo. White Phosphorus is used to make red phosphorus rodenticides used to make matches or matches. Phosphorus compounds are also used to clarify the beet sugar solutions and special alloys such as phosphor bronzes. White phosphorus is used in the preparation of rat poison, insecticides and in the fireworks industry and red phosphorus is used to make matches.

In ordinary matches the head consists of a combustible mixture of sulfur and potassium chlorate plated phosphorus sulfide which ignites the heat produced by friction and in turn produce inflammation of the combustible mixture. Safety Matches In the head is composed of antimony sulfide mixed with potassium dichromate acts as an oxidant. Box scraper consists of red phosphorus and powdered glass. The heat of friction transforms a little red white phosphorus, which ignites and causes them to turn on the head.

Physical Properties

Solid ordinary state (diamagnetic)

Density 1823 kg/m3

Melting point 317.3 K (44 ° C)

Boiling point 550 K (277 ° C)

Enthalpy of vaporization 12,129 kJ / mol

Melting enthalpy of 0,657 kJ / mol

Vapor pressure 20.8 Pa at 294 K

Chemical Properties

Mean radius 100 pm

Electro negativity 2.19 (Pauling)

Atomic radius (calc) 98 pm (Bohr radius)

106 pm Covalent Radius

Van der Waals radius of 180 pm

State (s) of oxidation ± 3, 4, 5

Weakly acidic oxide

1. The ionization 1011.8 kJ / mol

Two. The ionization 1907 kJ / mol

Three. The ionization 2914.1 kJ / mol

April. The ionization 4963.6 kJ / mol

May. The ionization 6273.9 kJ / mol

Isotopes

The most abundant isotope phosphorous 31 (15 protons and 16 neutrons) stable. There are two synthetic isotopes: the P 32 (15 protons and 17 neutrons) and phosphorus 33 (15 protons and 18 neutrons). Both are very unstable and emit beta radiation sulfur. The cores becoming P 32 has medical uses and the P 33 in research.

Physical Characteristics

•

Phosphorus is an essential component of organisms.

•

Part of nucleic acids (DNA and RNA).

•

They are part of the bones and teeth of animals.

•

In plants in a portion of 0.2% in the animals up to 1% of their mass is phosphorus.

•

The common is a solid match.

•

From white, but pure is colorless.

•

A characteristic odor.

•

Is a nonmetal.

•

Emits light by phosphorescence.

There are several allotropic forms of phosphorus being the most common white phosphorus and red, both forming four-atom tetrahedral structures. Whitephosphorus, extremely toxic and flammable two forms, alpha and beta, with a transition temperature of -3.8 °C, exposed to sunlight or heat (300 °C) becomes exothermic red phosphorus. This is more stable and less volatile and toxic than white is normally found in laboratories and are manufactured with the matches. The black phosphorus has a structure similar to graphite conducts electricity, is denser than the other two states and not inflamed.

Acids and Bases

By the 1884 definition of Svante Arrhenius (Sweden), an acid is a material that can release a proton or hydrogen ion (H +). Hydrogen chloride in water solution ionizes and becomes hydrogen ions and chloride ions. If that is the case, a base, or alkali, is a material that can donate a hydroxide ion (OH-). Sodium hydroxide in water solution becomes sodium ions and hydroxide ions. By the definition of both Thomas Lowry (England) and J.N. Brønsted (Denmark) working independently in 1923, an acid is a material that donates a proton and a base is a material that can accept a proton. Was Arrhenius erroneous? $| 8-)  No. The Arrhenius definition serves well for a limited use. We are going to use the Arrhenius definitions most of the time. The Lowry- Brønsted definition is broader, including some ideas that might not initially seem to be acid and base types of interaction. Every ion dissociation that involves a hydrogen or hydroxide ion could be considered an acid- base reaction. Just as with the Arrhenius definition, all the familiar materials we call acids are also acids in the Lowry - Brønsted model. The G.N. Lewis (1923) idea of acids and bases is broader than the Lowry - Brønsted model. The Lewis definitions are: Acids are electron pair acceptors and bases are electron pair donors.

 

We can consider the same idea in the Lowry - Brønsted fashion. Each ionizable pair has a proton donor and a proton acceptor. Acids are paired with bases. One can accept a proton and the other can donate a proton. Each acid has a proton available (an ionizable hydrogen) and another part, called the conjugate base. (That word, 'conjugate' just means that it "goes with" the other part.) When the acid ionizes, the hydrogen ion is the acid and the rest of the original acid is the conjugate base. Nitric acid, HNO 3, dissociates (splits) into a hydrogen ion and a nitrate ion. The hydrogen almost immediately joins to a water molecule to make a hydronium ion. The nitrate ion is the conjugate base of the hydrogen ion. In the second part of the reaction, water is a base (because it can accept a proton) and the hydronium ion is its conjugate acid.

 

In a way, there is no such thing as a hydrogen ion or proton without anything else. They just don't exist naked like that in water solution. Remember that water is a very polar material. There is a strong partial negative charge on the side of the oxygen atom and a strong partial positive charge on the hydrogen side. Any loose hydrogen ion, having a positive charge,  would quickly find itself near the oxygen of a water molecule.

At close range from the charge attraction, the hydrogen ion would find a pair (its choice of two pairs) of unshared electrons around the oxygen that would be capable of filling the its outer shell. Each hydrogen ion unites with a water molecule to produce a hydronium ion, (H3O)+, the real species that acts as acid. The hydroxide ion in solution does not combine with a water molecule in any similar fashion. As we write reactions of acids and bases, it is usually most convenient to ignore the hydronium ion in favor of writing just a hydrogen ion, (H+).

Formulation

Formulation is a term used in various senses in various applications, both the material and the abstract or formal. Its fundamental meaning is the putting together of components in appropriate relationships or structures, according to a formula. It might help to reflect that etymologically Formula is the diminutive of the Latin Forma, meaning shape.

In that sense a formulation is created according to the standard for the product.

Abstract applications

Disciplines in which one might use the word formulation in the abstract sense include Logic, Mathematics, Linguistics, Legal theory, and Computer science. For details, see the related articles.

Material applications

In more material senses the concept of formulation appears in the physical sciences, such as physics, chemistry, and biology. It also is ubiquitous in industry, engineering and medicine, especially pharmaceutics.

History

History

 

First systemization attempts

In 1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths; Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third; this became known as the Law of Triads. German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.

In 1858, German chemist August Kekulé observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms.

In 1862, Alexandre-Emile Béguyer de Chancourtois, a French geologist, published an form of periodic table, which he called the telluric helix or screw. He was the first person to notice the periodicity of the elements. With the elements arranged in a spiral on a cylinder by order of increasing atomic weight, de Chancourtois showed that elements with similar properties seemed to occur at regular intervals. His chart included some ions and compounds in addition to elements. His paper also used geological rather than chemical terms and did not include a diagram; as a result, it received little attention until the work of Dmitri Mendeleev.

In 1864, Julius Lothar Meyer, a German chemist, published a table with 44 elements arranged by valency. The table showed that elements with similar properties often shared the same valency. Concurrently, William Odling (an English chemist) published an arrangement of 57 elements, ordered on the basis of their atomic weights. With some irregularities and gaps, he noticed what appeared to be a periodicity of atomic weights amongst the elements and that this accorded with 'their usually received groupings.' Odling alluded to the idea of a periodic law but did not pursue it. He subsequently proposed (in 1870) a valence-based classification of the elements.

Newlands's periodic table, 

as presented to the Chemical Society in 1866, and based on the law of octaves English chemist John Newlands produced a series of papers from 1863 to 1866 noting that when the elements were listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals of eight; he likened such periodicity to the octaves of music. This so termed Law of Octaves, however, was ridiculed by Newlands' contemporaries, and the Chemical Society refused to publish his work. Newlands was nonetheless able to draft a table of the elements and used it to predict the existence of missing elements, such as germanium. The Chemical Society only acknowledged the significance of his discoveries five years after they credited Mendeleev.

In 1867, Gustavus Hinrichs, a Danish born academic chemist based in America, published a spiral periodic system based on atomic spectra and weights, and chemical similarities. His work was regarded as idiosyncratic, ostentatious and labyrinthine and this may have militated against its recognition and acceptance.

Periodic Table

The periodic table is a tabular arrangement of the chemical elements, organized on the basis of their atomic numbers, electron configurations, and recurring chemical properties. Elements are presented in order of increasing atomic number (number of protons). The standard form of the table comprises an 18-column-by-7-row main grid of elements, with a double row of elements below. The table can also be deconstructed into four rectangular blocks: the s-block to the left, the p-block to the right, the d-block in the middle, and the f-block below that.

The rows of the table are called periods; the columns are called groups, with some of these having names such as halogens or noble gases. Since, by definition, a periodic table incorporates recurring trends, any such table can be used to derive relationships between the properties of the elements and predict the properties of new, yet to be discovered or synthesized, elements. As a result, a periodic table—whether in the standard form or some other variant—provides a useful framework for analyzing chemical behavior, and such tables are widely used in chemistry and other sciences.

 

Although precursors exist, Dmitri Mendeleev is generally credited with the publication, in 1869, of the first widely recognized periodic table. He developed his table to illustrate periodic trends in the properties of the then-known elements. Mendeleev also predicted some properties of then-unknown elements that would be expected to fill gaps in this table. Most of his predictions were proved correct when the elements in question were subsequently discovered. Mendeleev's periodic table has since been expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behavior.

All elements from atomic numbers 1 (hydrogen) to 118 (ununoctium) have been discovered or synthesized. The elements from 1 to 98 (californium) have been found to exist naturally, although some [n 1] are found only in trace amounts and were initially discovered by synthesis in laboratories. The elements after 98 have only been synthesized in laboratories. Production of elements beyond ununoctium is being pursued, with the question of how the periodic table may need to be modified to accommodate any such additions being a matter of ongoing debate. Numerous synthetic radionuclides of naturally occurring elements have also been produced in laboratories.

Layout

All versions of the periodic table include only chemical elements, not mixtures, compounds, or subatomic particles.[n 2] Each chemical element has a unique atomic number representing the number of protons in its nucleus. Most elements have differing numbers of neutrons among different atoms, with these variants being referred to as isotopes. For example, carbon has three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent has seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. Elements with no stable isotopes have the atomic masses of their most stable isotopes, where such masses are shown, listed in parentheses.

In the standard periodic table, the elements are listed in order of increasing atomic number (the number of protons in the nucleus of an atom). A new row (period) is started when a new electron shell has its first electron. Columns (groups) are determined by the electron configuration of the atom; elements with the same number of electrons in a particular subshell fall into the same columns (e.g. oxygen and selenium are in the same column because they both have four electrons in the outermost p-subshell). Elements with similar chemical properties generally fall into the same group in the periodic table, although inthe f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.

As of 2012, the periodic table contains 118 confirmed chemical elements. Of these elements, 114 have been officially recognized and named by the International Union of Pure and Applied Chemistry (IUPAC). A total of 98 of these occur naturally, of which 84 are primordial. The other 14 natural elements only occur in decay chains of primordial elements.[3] All elements from einsteinium to copernicium, as well as flerovium and livermorium, while not occurring naturally in the universe, have been duly synthesized and officially recognized by the IUPAC. Elements 113, 115, 117 and 118 have reportedly been synthesized in laboratories but these reports have not yet been confirmed. As such these elements are currently known only by their systematic element names, based on their atomic numbers. No element heavier than einsteinium (element 99) has ever been observed in macroscopic quantities in its pure form. No elements past 118 have been synthesized as of 2012.

Grouping methods

•

Groups

A group or family is a vertical column in the periodic table. Groups usually have more significant periodic trends than periods and blocks, explained below. Modern quantum mechanical theories of atomic structure explain group trends by proposing that elements within the same group generally have the same electron configurations in their valence shell. Consequently, elements in the same group tend to have a shared chemistry and exhibit a clear trend in properties with increasing atomic number. However in some parts of the periodic table, such as the d-block and the f-block, horizontal similarities can be as important as, or more pronounced than, vertical similarities.

Under an international naming convention, the groups are numbered numerically from 1 to 18 from the leftmost column (the alkali metals) to the rightmost column (the noble gases). Previously, they were known by roman numerals. In America, the roman numerals were followed by either an "A" if the group was in the s- or p-block, or a "B" if the group was in the d-block. The roman numerals used correspond to the last digit of today's naming convention (e.g. the group 4 elements were group IVB, and the group 14 elements was group IVA). In Europe, the lettering was similar, except that "A" was used if the group was before group 10, and "B" was used for groups including and aftergroup 10. In addition, groups 8, 9 and 10 used to be treated as one triple-sized group, known collectively in both notations as group VIII. In 1988, the new IUPAC naming system was put into use, and the old group names were deprecated.

Some of these groups have been given trivial (unsystematic) names, as seen in the table to the right, although some are rarely used. Groups 3–10 have no trivial names and are referred to simply by their group numbers or by the name of the first member of their group (such as 'the scandium group' for Group 3), since they display fewer similarities and/or vertical trends.

 

Elements in the same group tend to show patterns in atomic radius, ionization energy, and electro negativity. From top to bottom in a group, the atomic radii of the elements increase. Since there are more filled energy levels, valence electrons are found farther from the nucleus. From the top, each successive element has lower ionization energy because it is easier to remove an electron since the atoms are less tightly bound. Similarly, a group has a top to bottom decrease in electro negativity due to an increasing distance between valence electrons and the nucleus. There are exceptions to these trends, however, an example of which occurs in group 11 where electro negativity increases farther down the group.

•

Periods

A period is a horizontal row in the periodic table. Although groups generally have more significant periodic trends, there are regions where horizontal trends are more significant than vertical group trends, such as the f-block, where the lanthanides and actinides form two substantial horizontal series of elements.

Elements in the same period show trends in atomic radius, ionization energy, electron affinity, and electro negativity. Moving left to right across a period, atomic radius usually decreases. This occurs because each successive element has an added proton and electron which causes the electron to be drawn closer to the nucleus. This decrease in atomic radius also causes the ionization energy to increase when moving from left to right across a period. The more tightly bound an element is, the more energy is required to remove an electron. Electro negativity increases in the same manner as ionization energy because of the pull exerted on the electrons by the nucleus. Electron affinity also shows a slight trend across a period. Metals (left side of a period) generally have a lower electron affinity than nonmetals (right side of a period), with the exception of the noble gases.