Periodic Table of the elements

The periodic table of elements classifies, organizes and distributes various chemicals, according to their properties and characteristics.

Usually attributed Dmitri Mendeleev's table, who ordered the items based on the manual variation of the chemical, while Julius Lothar Meyer, working separately, conducted a system from the physical properties of atoms. The current form is a modified version of Mendeleev, was designed by Alfred Werner.

Groups

Main article: Group of the Periodic Table

A vertical column of the periodic table are called groups. All elements belonging to a group have the same valence atomic and therefore have similar characteristics or properties with each other. For example, elements in group IA have valence 1 (one electron in its last energy level) and all tend to lose that electron to the positive ions bind as +1. Items in the last group on the right are the noble gases, which have filled their last energy level (octet rule) and therefore are all extremely unreactive.

Numbered from left to right, according to the latest IUPAC recommendation (and brackets under the old proposal of the IUPAC), the groups of the periodic table are:

Group 1 (I A): the alkali metals

Group 2 (IIA) Alkaline earth metals

Group 3 (III B): Family of scandium

Group 4 (IV B): Family of Titanium

Group 5 (V B): Family of vanadium

Group 6 (VI B): Family Chrome

Group 7 (VII B): Family of Manganese

Group 8 (VIII B): Family of Iron

Group 9 (VIII B): Family of Cobalt

Group 10 (VIII B): Nickel Family

Group 11 (IB): Copper Family

Group 12 (IIB): Family of Zinc

Group 13 (IIIA): the earth

Group 14 (IV A): the carbonoideos

Group 15 (V A): the nitrogenoideos

Group 16 (VI A): the chalcogens or anfígenos

Group 17 (VIIA): the halogens

Group 18 (VIII): noble gases

The sub-terrestrial

1. Atmosphere

The atmosphere is the gaseous part of the Earth, and is thus the outer layer and less dense planet. It consists of several gases that vary in amount depending on the pressure at various altitudes. This mixture of gases that form the atmosphere receives the generic name of air. 75% of atmospheric mass is in the first 11 km high from the sea surface. The main constituent elements are oxygen (21%) and nitrogen (78%).

2. Hydrosphere

The hydrosphere or hydrosphere (Greek hydros, water and sphaira: field) described in the Earth Sciences the material system consisting of the water is low, and on the surface of the Earth.

The water that forms the hydrosphere is divided between various compartments in descending order of volume are:

ü The oceans, which cover two thirds of the earth's surface with a typical depth of 3000 to 5000 meters.

ü The glaciers that cover part of the land surface. Especially the two ice sheets of Greenland and Antarctica, but mountain glaciers and volcano, many smaller thickness at all latitudes.

üSurface runoff, a very dynamic system formed by rivers and lakes.

üGroundwater, which is embedded in porous rock more or less universal.

üEn la atmósfera en forma de nubes.

üEn la biosfera, formando parte de plantas, animales y
seres humanos.

3. Geósfera

The geosphere is the structural part of the Earth that extends from the surface to the interior of the planet (about 6740 km). This layer is characterized by a rock structure that supports the rest of the other terrestrial systems, as the biosphere and atmosphere, located these on the most superficial.

4. Biosfera

In ecology, the biosphere and biosphere is the material system consists of a group of living beings own planet Earth, along with the physical environment around them and they help shape. This meaning of "wrapping live" Earth is the most widely used, but also speaks of biosphere times to refer to the space within which life develops, the biosphere is also the whole of the lithosphere, hydrosphere and the atmosphere.

The biosphere is the global ecosystem. At the same concept we refer to other terms that can be considered synonyms, as ecosphere or biogeosfera. It is a collective creation of a variety of organisms and species interacting with each other, form the diversity of ecosystems. It has properties that allow us to speak of it as a great living being, able to control, within limits, their own state and evolution.

Earth's internal structure

The interior of the planet, like the other terrestrial planets (planets whose volume is occupied mainly of rocky material), is divided into layers. The Earth has an outer shell of solidified silicates, a viscous mantle and a core with two layers, an outer semi-solid, much more fluid than the inner mantle and a solid. Many of the rocks that now form part of the crust formed less than 100 million (1 × 108) years. However, the oldest known mineral formations are 4,400 million (44 × 108) years, which indicates that, at least, the planet has a solid crust since.

Much of our knowledge about the interior of the Earth has been inferred from other observations. For example, the force of gravity is a measure of the landmass. After knowing the volume of the planet, we can calculate its density. The calculation of mass and volume of surface rocks, and water bodies, allow us to estimate the density of the outer layer. The mass is the atmosphere or in the crust must be in the inner layers.

Estructura

The structure of the earth can be established according to two different criteria. According to their chemical composition, the planet can be divided into crust, mantle and core (external and internal), according to their physical properties are defined lithosphere, asthenosphere, mesosphere and the nucleus (external and internal).

The layers are within the following depths:

Layer	Depth (km)
Lithosphere (locally varies between 5 and 200 km)	0 – 60
... Crust (locally varies between 5 and 70 km)	0 – 35
... Upper mantle	35 – 60
Mantle	35 – 2 890
Upper mantle	35 – 660
... asthenosphere	100 – 200
Lower Mantle (Mesosphere)	660 – 2 890
Outer core	2 890 – 5 100
Inner Core	5 100 – 6 378

The division of land in layers has been determined indirectly using the time it takes to travel the reflected and refracted seismic waves created by earthquakes. Shear waves (S, or secondary) can not pass through the core, because they need a viscous material or elastic to spread, while the speed of propagation is different in the other layers. Changes in that rate due to produce a Snell refraction. The reflections are caused by a large increase in seismic velocity (speed of propagation) and are similar to reflection in a mirror.

Geological Timescale

The geologic time scale and geologic time scale is the framework to represent the events of Earth history in chronological order. Set divisions and subdivisions of the rocks according to their relative age and absolute time elapsed since the formation of the Earth to the present, in two dimensions: stratigraphic and chronological. These divisions are based primarily on faunal changes observed in the fossil record and have been dated by radiometric methods. The scale summarizes and unifies the results of work performed for centuries by naturalists, geologists, paleontologists and many other specialists. Since 1974 the formal elaboration of the scale is done by the International Commission on Stratigraphy of the International Union of Geological Sciences and the changes after several years of studies and discussions of specific subcommittees, must be ratified at conferences worldwide.

Geologic time scale

Schedule at

The diagram below shows the length scale of each geological period. The second and third schedule represent the subsections marked with asterisks in the immediately preceding it.

Continental drift

Continental drift is the movement of continental masses relative to each other. This hypothesis was developed in 1912 by the German Alfred Wegener from various empirical observations, but it was not until the 60's, with the development of plate tectonics, he was able to adequately explain the movement of continents.

Plate tectonics, earthquakes.

A plate tectonic or lithospheric plate is a piece of lithosphere that moves as a rigid block without internal deformation present on the Earth's asthenosphere.

Plate tectonics is the theory that explains the structure and dynamics of Earth's surface. It states that the lithosphere (the upper cooler and rigid Earth) is fragmented into a series of plates that move over the mantle. This theory also describes the plate motion, their addresses and interactions. The earth's lithosphere is divided into large plates and plates less than or microplates. At the edges of the plates is concentrated seismic activity, volcanic and tectonic. This leads to the formation of large chains and basins.

Earth is the only planet in the Solar System with active tectonic plates, although there is evidence that Mars, Venus and some of lossatélites Galilean, like Europe, was tectonically active in ancient times.

Seismic

An earthquake is a vibration caused by the mass loss of stability of bark. When the motion reaches the surface and spreads it will call earthquake.

Earthquakes and volcanoes

Earthquakes

An earthquake, earthquake or earthquake also called (from the Greek "σεισμός" tremor) or tierra1 tremor is a shaking of the ground produced by the collision of tectonic plates and the release of energy in the course of a sudden reorganization of materials Earth's crust to overcome the state of mechanical equilibrium. The most important and frequently occur when releasing stored elastic potential energy in the gradual deformation of the rocks adjacent to an active fault plane, but can also occur from other causes, such processes around volcanic or karst cavities collapse.

Volcanoes

A volcano (the mythological god Vulcan) is a tube placed in direct communication the top of the solid crust with lower levels of it. It is also a geological structure which emerge from the magma (molten rock) as lava and gases from the interior. The rise usually occurs in episodes of violent activity called "rash", which can vary in intensity, duration and frequency, being from conduit lava flows extremely destructive to explosions.

Generally acquire a characteristic conical shape is formed by magma pressure and the accumulation of material from previous eruptions. Can be found above the volcano whose crater or caldera.

Volcanoes can be found on Earth and other planets and satellites, some of which are made of materials that we consider "cool" these are the cryovolcanoes. That is, they rock acts as the ice cold water while the internal liquid acts as the magma, that happens, for example in the cold Jupiter's moon Europa.

Usually, the volcanoes are formed at the boundaries of tectonic plates, although there are exceptions called hot spots or hot spots located in the interior of tectonic plates, such as the Hawaiian Islands. There are also underwater volcanoes that can remove enough material to form volcanic islands.

Geologists have classified into three categories volcanoes: shield volcanoes, cinder cones and composite cones (also called stratovolcanoes)

Types of Rocks

The rocks can be classified according to their properties such as chemical composition, texture, permeability, among others. In any case, the criterion used is the origin, ie the mechanism of their formation. According to this criterion are classified as igneous (or magma), sedimentary and metamorphic rocks, but can be considered a separate class of altered rocks, which are studied more often among the sediments.

Igneous or magmatic

Are formed by the solidification of magma, a molten mineral mass includes volatile dissolved gases. The process is slow, when it occurs in the depths of the cortex, or faster, if it happens on the surface. The result in the first case, plutonic or intrusive rocks, consisting of thick glasses and recognizable volcanic or extrusive rocks when the magma reaches the surface, become lava degassing.

Las rocas magmáticas intrusivas son con mucho las más abundantes, forman la totalidad del manto y las partes profundas de la corteza. Son las rocas primarias, el punto de partida para la existencia en la corteza de otras rocas.

Depending on the starting magma composition, more or less rich in silica (SiO2), are classified in Ultramafic (or ultrabasic), mafic, intermediate and or sialic acid, the latter being the richest in silica. They are usually more acidic the most superficial.

The original structures of igneous rocks are the plutons, massive forms originated at great depth,the levees ,formed in the ground and filled with cracks,and lava flows ,lava flows on the surface cooled . A special case is that of the pyroclastic deposits formed by falling volcanic bombs, ash and other materials thrown into the air more or less explosive eruptions. The volcanic cones are formed with these materials, sometimes alternating with solidified lava flows (stratified cones).

Sedimentary rocks

Are formed by diagenesis (compaction and cementation) of sediment material from the surface alteration of other rocks, which are then transported and deposited by water, ice and wind, with the help of gravity or by precipitation from solutions . Also classified as sedimentary deposits organogenic materials formed by living organisms such as coral reefs, the strata of coal or oil deposits. Sedimentary rocks are those that typically have fossil remains of living organisms, although they can also be seen in some metamorphic rocks of sedimentary origin.

Sedimentary rocks are formed in the sedimentation basins, the hollows of the land to which the material carried by erosion are conducted with the help of gravity. The original structures of the sedimentary rocks are called strata, layers formed by deposition, which are formations often high power (thick).

Metamorphic rocks

Strictly is any metamorphic rock that has been produced by the evolution of a previous application to be subjected to an environment is very different from the energy of its formation, much hotter or colder, or a very different pressure. When this happens, the rock tends to evolve to stable features that make under these new conditions. The most common is the progressive metamorphism, which occurs when the rock is subjected to heat or higher pressure, but without mixing (because then we enter the realm of magmatism), but there is also a concept of regressive metamorphism, when evolved rock at great depth - under conditions of high temperature and pressure - happens to be in the area, or near where it is unstable and evolves to just that one factor triggering the process.

Metamorphic rocks are abundant in deep areas of the cortex, above the magmatic socket. Tend to distribute classified in areas other than the degree of metamorphism, as the effect of the factor involved. For example, when the cause is the heat released from a bag of magma, rocks form a halo concentric zones around the magmatic pluton. Many metamorphic rocks show the effects of pressure addressed, they do evolve to other layered minerals, and take a look laminate. Examples of metamorphic rocks are slate, marble or quartzite.

The atmosphere

The atmosphere is the gaseous part of the Earth, and is thus the outer layer and less dense on the planet. Consists of several gases that vary in amount depending on the pressure at various altitudes. This mixture of gases to the atmosphere is generally receives the name of air. 75% of atmospheric mass is in the first 11 km high from the sea surface. The main constituent elements are oxygen (21%) and nitrogen (78%).

The atmosphere and hydrosphere are the smooth surface layer system on the planet, whose dynamic movements are closely related. Air currents drastically reduce temperature differences between day and night, distributing heat around the planet's surface. This closed system prevents the nights are chilly and the days are extremely hot.

The atmosphere protects life on Earth by absorbing much of the solar ultraviolet radiation in the ozone layer. It also acts as a shield against meteorites, which are crushed to powder by friction suffering to make contact with the gases.

Layers of Earth's atmosphere

Troposphere

Its main features are:

· Its thickness ranges from the Earth's surface (both land and aquatic or marine) to an altitude varying between 6 km in the polar areas and 18 or 20 km in the tropics, for the reasons given below.

· The bottom layer of the troposphere is called the geographic layer, which is where the greater proportion of geographic features, both in the field of physical geography in the field of human geography.

· The latitude of the place more or less determines the thickness of the troposphere, being much higher in the tropics by the centrifugal force of earth rotation and much lower in the polar regions for the same reason (polar flattening).

Stratosphere

Its name comes from which is arranged in more or less horizontal layers (or strata) 9 / 18 - 50 km, the temperature remains constant and then increase with altitude. The stratosphere is the second layer of the Earth's atmosphere. As it rises, the stratospheric temperature increases. This temperature increase is due to ultraviolet rays convert oxygen into ozone, a process involving heat, to ionize the air, it becomes a good conductor of electricity and thus heat. That is why at some point there is a relative abundance of ozone (ozone layer), which also implies that the temperature is raised to 80 ° C or more. However, that temperature has practically no meaning, since it is a rarefied atmosphere, very tenuous.

Ozonosphere

Called ozone, or ozone layer, the area of Earth's stratosphere containing relatively high concentrations of ozone. This layer, which extends approximately 15 km to 40 km altitude, meets 90% of ozone in the atmosphere and absorbs 97% to 99% of high-frequency ultraviolet radiation.

Mesosphere

It is the third layer of the Earth's atmosphere. It extends between 50 and 80 km in height, containing only 0.1% of the total mass of air. It is the coldest zone of the atmosphere, and can reach -80 ° C. It is important for the ionization and chemical reactions that occur in it. The low air density in the mesosphere determines the formation of turbulence and atmospheric waves operating at spatial and temporal scales very large.

Ionosphere

The thermosphere and ionosphere: 69/90 - 600/800 km, temperature increases with altitude. Thermosphere is the fourth layer of the Earth's atmosphere. It is located above the mesosphere. At this point, the air is thin and the temperature change with solar activity. If the sun is active, the thermosphere temperatures can reach 1,500 ° C or even higher. Earth's thermosphere also includes the region called the ionosphere. It is 0.1% of the gases.

Exosphere

The last layer of the Earth's atmosphere is the exosphere (600/800 - 2.000/10.000 km). This is the area where the atoms escape into space.

Atmospheric circulation

The atmospheric circulation is a movement of large-scale atmospheric air and ocean circulation together with the means by which heat is distributed over the surface of the Earth. However, it should be noted that although the role of ocean currents is smaller in accordance with its volume compared with the atmospheric circulation, its importance in terms of heat flow between areas geoastronómicas is very large for the remarkable difference in density between the atmosphere and the oceans that causes the specific heat transported by ocean water m³ is much higher than that can move a m³ of air.

Weather

The atmosphere and climate

The hydrosphere and its dynamics

Hydrosphere hydrosphere or described in the Earth Science material system consisting of the water is low, and on the surface of the Earth.

The water that forms the hydrosphere is divided among several compartments in order from largest to smallest volume are:

· The oceans, which cover two thirds of the Earth's surface with a typical depth of 3000 to 5000 meters.

· The glaciers that cover part of the land surface. Particularly the two ice sheets of Greenland and Antarctica, but mountain glaciers and volcano, smaller in size and thickness at all latitudes.

· Surface runoff, a very dynamic system formed by rivers and lakes.

· Groundwater, which is embedded in porous rock more or less universal.

· In the atmosphere as clouds.

· In the biosphere, as part of plants, animals and humans.

Dynamics of the hydrosphere

Internal cycle: The water comes from the mantle by volcanism at mid-ocean, a fraction of the sea water enters the ocean crust and becomes inserted into subduction zones and part is reinjected into the mantle. The amount of water reintroduced into the mantle to compensate exiting the ridges.

External cycle: It is the cyclical movement of water through evaporation ascending descending by precipitation and runoff.

The amount of evaporated ocean water is greater than that received by rainfall. The opposite occurs on the continents, the precipitated amount is greater than the evaporated on the continents, this excess is returned to the oceans via stormwater runoff on the topography of the area.

Cell

A cell (Cell Latin, diminutive of cellam, cell, small room) is the morphological and functional unit of all living things. In fact, the cell is the smallest element that can be considered alive. Thus, can be classified living organisms according to the number of cells that have: if you only have one, are called unicellular (such as protozoa or bacteria, microscopic organisms), if they have more, they are called multicellular. In the latter the number of cells varies from a few hundreds, and in some nematodes, hundreds of billions (1014), as in the case of human beings. The cells usually have a size of 10 microns and a mass of 1 ng, while cells are much larger.

The cell theory, proposed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, postulates that all organisms are composed of cells and all cells derived from other precedents. Thus, all vital functions emanating from the cellular machinery and the interaction between adjacent cells, in addition, possession of genetic information, the basis of heredity, in its DNA allows the transmission of it from generation to generation.

The appearance of the first living organism on Earth is usually associated with the birth of the first cell. While there are many hypotheses speculate how it happened, it usually describes the process started by the transformation of inorganic into organic molecules under appropriate environmental conditions, after that, those associated biomolecules leading to complex capable of self-replicating entities. There are possible fossil evidence of cellular structures in rocks dated to around 4 or 3.5 billion years (Ga giga-years.). Evidence of the presence of life based on deviations from isotopic ratios are above (Isua supracrustal belt, 3.85 Ga.).

There are two main types of cells: prokaryotes (cells comprising archaea and bacteria) and eukaryotes (traditionally divided into animal and plant, while also including fungi and protists, which also have cells with characteristic properties).

History and cellular theory

The first approaches to the study of cell emerged in the seventeenth century, following the development in the late sixteenth of the first microscopes. These allowed for numerous comments, which led in only two hundred years morfológicorelativamente acceptable knowledge. The following is a brief chronology of these discoveries:

1665: Robert Hooke published the results of his observations on plant tissues, such as cork, made with a microscope of 50 increases built by himself. The researcher was the first, seeing in those tissues that were repeated units in the form of cells of a honeycomb, christened as elements of repetition, "cells" (Latin for cell, cells). But Hooke could only watch as dead cells could not describe the structures inside.

Early 1670: Anton van Leeuwenhoek observed various eukaryotic cells (such as protozoa and spermatozoa) and prokaryotes (bacteria).

1745: John Needham described the presence of "animalcules"or "infusoria": it was single-celled organisms.

Illustration of the structure observed by Robert Hooke cork under a microscope and as published in Micrographia.

Early 1830: Theodor Schwann cell studied animal with Matthias Schleiden postulated that cells are the basic units in the formation of plants and animals, and are the foundation of the life process.

1831: Robert Brown described the cell nucleus.

1839: observed Purkinje cell cytoplasm.

1850: Rudolf Virchow postulated that all cells come from other cells.

1857: Kölliker identified the mitochondria.

1860: Pasteur conducted many studies on the metabolism of yeasts and asepsis.

1880: August Weismann found that the current cell and molecular structural similarity shared with cells from ancient times.

1931: Ernst Ruska construyó el primer microscopio electrónico de transmisión en la Universidad de Berlín. Cuatro años más tarde, obtuvo un poder de resolución doble a la del microscopio óptico.

1981: Lynn Margulis published her serial endosymbiosis hypothesis, which explains the origin of the eukaryotic cell.

Diversity of life, levels of organization of living beings.

For the study of life, is part of the traditional classification of the two large groups: the animal kingdom and plant kingdom. But going into details and detailed studies, are beings who share certain characteristics of both kingdoms.

In this the reason why many biologists believe more desirable to state four kingdoms:


1. Moneras or Prokaryotes: Formed by bacteria and blue algae. According to Whittaker, along with bacteria are the kingdom azuladosas algae or blue-green algae, and are prokaryotes.

• Are unicellular or colonial.
• With chlorophyll but not chloroplast.
• Fresh or salt water, there ADAF.
• Of autotrophic nutrition. Fix atmospheric nitrogen.
• They reproduce by fission.

2. Unicellular eukaryotic organism: protozoa, yeasts and unicellular algae.

3. Metafitas: Multicellular plants.

4. Metazoans: Multicellular animals.