Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
INTRODUCTION The present modern periodic table explains in detail and updated the properties of chemical elements based on their atomic structure .According its chemical properties, elements are classified as metals and non-metals. There are more than non-metallic metals. The same elements that are in earth exist on other planets from outer space. The student must know both classes, their physical properties and important chemical; not memorize, but familiar, so for example familiar with the valence of the main metallic and nonmetallic elements, not individually or in isolation, but by groups or families (I, II, III, etc.) and thereby learn easy and flexible formulas and names of chemical compounds, which is a vital part of the chemical language PERIODIC TABLE OF THE ELEMENTS The periodic table of elements classifies, organizes and distributes the various chemical elements according to their properties and characteristics; its main function is to establish a specific order grouping elements. Usually attributed to Dmitri Mendeleev table who ordered the items based on their chemical properties, although Julius Lothar Meyer, working separately, conducted a system from the physical properties of atoms. The current structure was designed by Alfred Werner from the version of Mendeleev. In 1952, the Costa Rican scientist Chaverri Gil (1921-2005) presented a new version based on the electronic structure of the elements version, which places the lanthanide and actinide series in a logical sequence according to their atomic number. The evolution of the classification of the elements has its main location moments groups of elements such as: Act 1829 Duberiener triads (groups of three elements with similar behavior) Act 1864 Newlands octaves (Groups of eight elements with similar behavior) 1869 Act periodic Mendeleev and Meyer (Order by increasing atomic mass) Moseley Act 1913 (Order by increasing atomic numbers) At present an atomic orbital is described by a particular permitted set of quantum and level values, shape and orientation, two electrons can occupy the same orbital only if their spins are opposite; in this case it is said that electrons are mismatched when occupying a single orbital or paired, when both occupy the same but with opposite spin orbital. For the first level there is only a maximum atomic orbital 1s and may have two electrons thus defining configurations for hydrogen 1s 1 and for helium 1s2, also electronic sequence that predicts the start of construction (Aufbaud) are built where the shape of fill levels and sublevels is defined as the energy as shown below: • Up and to the right increases the ionization energy, electron affinity and electronegativity. Some groups are better known by their specific name as: Group 1: Alkali metals Structure and organization of the periodic table The present periodic table is a system where the elements are sorted known to date. • They are placed from left to right and top to bottom in order of increasing atomic numbers. The elements are arranged in seven rows • Horizontal called periods, and in 18 vertical columns called groups or families. • Down and to the left increases the atomic radius and ionic radius. Group 2: alkaline earth metals Group 14 the carbonoideos Group 15 the nitrogenoideos Group 16 the anfigenos Group 17 halogens Group 18: the noble gases Periodic properties Many physical properties such as melting point, boiling point and atomic sizes show periodic variations according to the period (level) and the group they belong to the elements and knowledge to predict chemical behavior. Atomic Radius: Atomic radii decrease from left to right in groups and decrease in low-up periods. Ionization energy: is the amount of energy required to remove an electron less attracted to the nucleus in an atom is called the ground state and first ionization energy. The electron affinity: is the amount of energy required to add an electron to an isolated gaseous atom to form an anion (negatively charged ion). The ionic radius: Ions formed either losing electrons (to overcome the ionization energy) or gain electrons (to overcome the electron affinity). The general trend of the ionic radii is increased from left to right in the period and up and down the groups. Electronegativity: the tendency of an atom to attract electrons when it combines chemically with other atoms. Melting item: The periodic behavior of the melting item has a tendency to increase during periods of increased left to right and from bottom to top in the groups. External transition for a tendency to reduce its melting point in the periods from left to right and increase in the groups; in the inner transition elements values are consistent trend. Boiling item: for the representative elements there is a tendency to increase from bottom to top in IA, IIA, IIIA and IVA groups. The elements of internal and external transition there is a tendency to reduce the boiling point periods and increase with level. CONCLUSION From the periodic table of the chemical element necessary information is obtained, as regards its internal structure and properties, either physical or chemical. The periodic table was designed so that the elements that share similar properties are arranged in a column named group. This facilitates the study and comparison of the different elements. BIBLIOGRAPHY http://www.monografias.com/trabajos 68/tabla-periodica/tablaperiodica3.shtml http://www.angelfire.com/biz/diegolim/ quimica.html http://es.wikipedia.org/wiki/Tabla_peri %C3%B3dica_de_los_elementos