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)