Carbon group

The name carbon group (also carbon-silicon group ) refers to the 4th main group ( " Tetrels " ) ( according to the new numbering of IUPAC group 14) of the periodic table. It comprises the elements carbon (C ), silicon (Si), germanium (Ge), tin (Sn) and lead (Pb). Also, a radioactive element that Flerovium (Fl) is represented.

Diamonds

C60 fullerene

High-purity silicon

Silicon powder

Germanium

α and β tin

Lead

Properties

The elements of the group of carbon have very different chemical and physical properties, because the group is divided by the dividing line between metals and non-metals in two parts. The first element of the group carbon, is a non-metal, the two following ( silicon and germanium) are semi-metals and any additional ( tin, lead and Flerovium ) are metals.

Physical Properties

With increasing atomic number atomic mass grow, atomic radius and ionic radius. The density of graphite (C) and silicon are close together ( about 2.3 kg/dm.sup.3 ), it rises within the main group to lead on 11.34 kg/dm.sup.3. In the Mohs hardness there is also a large wingspan, up to 1.5 minimum ranges from a maximum of 10 for diamond in tin. The highest electrical conductivity tin with 9.17 MS / m, the smallest has silicon to 25.2 mS / m. The first ionization energy decreases with increasing atomic number of 11.26 eV for carbon to 7.34 eV for tin from. Lead has 7.42 eV again a slightly higher value. The electronegativity decreases with increasing atomic number of 2.5 (C ) to 1.6 (Pb) tends to decline, outliers with 1.7 is the silicon.

Electron configuration

The electronic configuration is [ X] ys2yp2. The X indicates the period are used, in which the element is found for the electron configuration of a period of higher standing noble gas, and for the y must. Germanium from a (y -1) d10 orbital is present; and lead from there is also a (y -2) f14 orbital.

For the individual elements are the electron configurations:

  • Carbon: [ He] 2s22p2
  • Silicon: [ Ne ] 3s23p2
  • Germanium: [ Ar] 3d104s24p2
  • Zinn: [ Kr ] 4d105s25p2
  • Lead: [ Xe] 4f145d106s26p2
  • Flerovium (calculated): [ Rn] 5f146d107s27p2

The oxidation states are 4 and -4, with increasing atomic number but also gains the 2 oxidation state in importance.

Chemical reactions

Due to the large differences within the group it is difficult to specify a general reaction behavior, as this will vary from item to item. In the following equations, the E stands for an element of the carbon group.

  • Reaction with oxygen:
  • Reaction with hydrogen ( without chain formation, not spontaneous):
  • Reaction with water:
  • Reaction with halogens ( chlorine on the example ):

Chain formation

A special feature of the group 14 elements is their ability to form long-chain hydrogen compounds of the structure XH3 ( XH2 ) n- XH3. All hydrogen atoms are covalently bonded, but the stability of these compounds increases with increasing atomic number of the element from.

  • Hydrocarbons: The group of hydrocarbons is the most extensive, as the number of carbon atoms and thus the chain length are virtually no limits. A further specific feature of the carbon material is the ability to form stable double and triple bonds. With the hydrocarbons and their derivatives deals organic chemistry.
  • Silanes: the case of silicon, the ability to chain formation is already limited to a maximum of 15 Si - Si bonds. Double or even triple bonds are unstable at silicon and the following elements, but also the silanes are not among the most stable compounds.
  • Germane Germanium is capable only to a maximum of nine Ge-Ge bonds. This limits the possibilities of course, a strong.
  • Zinnwasserstoffe: In tin only a single Sn - Sn bond is possible. There are therefore only two compounds of this class: SnH4 and SnH3 - SnH3.
  • Lead hydrogen: Lead does not have the ability to chain formation. Only pBH4 is known, but also this link is almost unstable.

Also ring formations are possible, the molecular formula is then ( XH2 ) n

Compounds

  • Oxide (IV) hydroxides and acids Carbon dioxide ( CO2) is a triatomic linear built and, therefore, non-polar molecule, due to the stability of the C = O double bond, and is present in a gaseous aggregate state. In water it forms the fickle, weak carbonic acid ( H2CO3 ).
  • In silica (SiO2) exist exclusively single bonds. It is a solid and is composed of SiO4 tetrahedra which are linked to each other, all the vertices. In nature SiO2 occurs as quartz. Amorphous SiO2 ( silica ) is the essential component of the glass.
  • Germanium dioxide ( GeO 2 ) substantially corresponds to the silicon dioxide, but may also crystallize in the rutile structure. The latter reacts with water to the germanic acid ( H4GeO4 ).
  • Tin ( IV ) oxide ( SnO2 ) is a solid and insoluble in water.
  • Lead (IV ) oxide ( PbO2 ) is also an insoluble in water solid.
  • Carbon monoxide ( CO) is a toxic gas.
  • Silicon monoxide ( SiO) is a dark brown, amorphous solid of polymer ( SiO) x chains.
  • Silicones consist of three-dimensional networks of alternating silicon and oxygen, which are mostly located on the silicon atoms organic radicals ( eg, methyl groups (- CH3) ).
  • Lead (II ) oxide
  • Lead (II, IV) -oxide

Occurrence

The earth's crust consists of 27.7 % from elements of the carbon group. Of this amount, 99.8 % silicon, the second most abundant element in the earth's crust (after oxygen).

The remaining 0.2 % are broken down as follows:

  • 99.1 % carbon
  • 0.94 % lead
  • 0.02 % tin
  • 0.01 % germanium.

With the exception of germanium they occur under natural conditions in some native deposits.

Beryllium Fluorine Sodium Magnesium Aluminium Argon Titanium Chromium Manganese Cobalt Nickel Zinc Arsenic Selenium Bromine Rubidium Yttrium Zirconium Ruthenium Palladium Cadmium Indium Antimony Tellurium Barium Lanthanum Praseodymium Neodymium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Tantalum Tungsten Rhenium Osmium Iridium Bismuth Polonium Astatine Francium Radium Actinium Neptunium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Dubnium Bohrium Darmstadtium Copernicium Group (periodic table) Period (periodic table) Period 2 element Period 3 element Period 4 element Period 6 element Period 7 element Chemical element Siemens (unit) Carbon suboxide Lead(II,IV) oxide Plumbane Lead(II) oxide Crust (geology) Native metal Integrated Authority File
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