Why carbon almost always has four bonds even though it only has two unpaired electrons?
813547
Carbon's atomic number is six.  The innermost shell contains two electrons.  The next shell needs eight to be complete, but carbon has only four left.  Therefore, it needs four additional electrons to complete the shell.
260431
R-O-CH3 \n\n R is any carbon based group. I wish I had chem draw on this computer, but the structure is actually bent due to the symmetry (this involves group theory - a linear algebra based idea in quantum mechanics) of the orbitals involved in bonding. Its bent for the same reasons that water is bent, now your teachers may say that water is bent due to electronic repulsions but if thats true how come they draw the lone pairs so close to eachother??? Its because its not true, and its part of VSEPR theory which is just a practicle method of teaching structure to people who dont know too much physics, math, and chemistry.
387688
I have seen sulfur compounds with 2, 4, and 6 covalent bonds attached the the sulfur atom. I can't think of any sulfur compounds with 5 bonds around the sulfur atom at the top of my head.
965017
You need to know the number of valence electrons.  Carbon, for example, would want to pair with 4 other atoms.  If there were fewer atoms attached as in CH2O (only 3 attached to the carbon) then one of the atoms must be double bonded.  In this case it is the oxygen that would have the double bond.  You could deduce the approximate shape from the number of bonds.  It would be slightly distorted by the slight negative polarity of the oxygen atom.  Shape of a molecule is a complicated issue that I glossed over.
282510
There are only 6 neutrons in a carbon atom.  In addition to that there are the 6 protons that make a carbon atom a carbon atom.  Protons and neutrons have nearly the same mass so, and additionally there are 6 electons (very small in mass, comparitively) in an electrically neutral carbon atom so the atomic mass is slightly more than twice the mass of the protons.
844956
Zero.  Carbon has 4 valence electrons, so it likes to form 4 bonds to give it a stable octet.  C is the central atom in CBr4, and since it's hooked up with 4 things, it's happy, and got nothing left over.  CCl4, CF4, and CH4 are similar to it in that respect.
75751
if there is no double bond between two carbon atoms then it is saturated
703480
These chemicals have one thing in common, carbon atoms. Carbon atoms link in chains, like C-C-C. Carbon atoms "like" to have 4 bonds with other atoms. In each of the chemicals you named, the carbons are all single or double-bonded to other carbons; the other bonds are with hydrogen atoms.\n\nThese are the simplest "organic chemicals". It used to be thought that "organic" chemicals were produced by living things. Now they're known to be produced in outer space as well. So there are many possible "origins" for these molecules in that sense.\n\nMethane molecules have only one carbon atom; octane has 8. So you might say that all of these molecules have their origin in carbon atoms sharing bonds with other carbons.
8113
because the carbon-carbon bonds in a diamond are bonded to 4 other carbon atoms in a tetrahedron pattern which is much stronger than the graphite bonds which look almost like flat sheets and have very weak atomic bonds
580069
Tetrahedral arrangement at the methyl carbon. (4 bonding pairs, no lone pairs)\nTrigonal planar arrangement at the carbonyl carbon. (3 bonding pairs, no lone pairs)\nBent arrangement at the single-bonded oxygen. (2 bonding pairs, 2 lone pairs)
55267
There are lots of reasons why there are large number of organic compounds .I’m giving U few of them.\nCatenation: The tendency of an element to form chains of identical atoms is called catenation. This tendency is observed in the case of non-metals showing covalency of two or more. However, this property is maximum in carbon as it can combine with other carbon atoms by single, double or triple covalent bonds. The bonding can be extended to form long open chain (straight or branched) or closed ones. Catenation property depends upon the value of bond energy which is maximum in the case of carbon. \nBond:                                         C-C    Si-Si       S-S     P-P     N-N    O-O\nBond energy:                              83        54         54        50      39        35          (approximately)\n(kcal/mol)\n The stability or the strength of the bond decreases as the bond energy decreases. Hence, the tendency of catenation decreases in the following manner; C> Si ~ S > P > N > O\nTendency to combine with other non-metals: Carbon has the ability to form strong covalent bonds with many other atoms such as H, O, S, N, Cl, Br, I, etc. The C-C bond energy is approximately equals to the magnitude of bond energies between carbon and various other atoms.\nBond                                          C-C         C-H       C-O      C-Cl      C-N       C-Br\nBond energy                               83.0         97.0       86.0      81.0       73.0       68.0           (approximately)\n(kcal/mol)\nIsomerism is one of the reason also.
758383
Since the central atom, C, does not have any lone pair electrons on it, and it is bonded to 3 oxygen atoms, the general shape around the central atom is trigonal planar.  The hydrogen atom is bonded to one of the oxygen atoms.\n\nTrigonal planar indictates that all 4 atoms, C and three O, lie in a plane and that the O-C-O bond angle is 120o for all bonds.
728656
There isn't any longest one.\nThe atom carbon can form chains which means that you can always make a carbon chain longer by hooking up another C atom.\nMolecules like DNA have thousands of atoms.
789677
3 is incorrect.  Three of the carbon electrons are located in the three sp2 hybrid orbitals and the remaining electron sits in the lone p orbital (orthogonal/perpendicular) to the molecular plane.  It is this electron in the p orbital which "interacts" with the oxygen lone electron in it's unhybidized p orbital to form the pi bond.\n\nThere are no electrons left in the original carbon 2s orbital because these orbitals have been hybridized to the sp2 orbitals in order to allow for the three sigma bonds (one to each hydrogen and one to the oxygen atom)
723749
because of the number of bonds between the atoms and as well that there are 2 lone pair of electrons on the oxygen and only 1 on the nitrogen if the bonding occurs
846836
Carbon occurs in all organic life and is the basis of organic chemistry. This nonmetal also has the interesting chemical property of being able to bond with itself and a wide variety of other elements, forming nearly ten million known compounds. \n\nBecause of their unique properties, multi-carbon compounds exhibit extremely large variety and the range of application of organic compounds is enormous. They form the basis of or are important constituents of many products (paints, plastics, food, explosives, drugs, petrochemicals, and many others) and of course (apart from a very few exceptions) they form the basis of all life processes.\n\nThe different shapes and chemical reactivities of organic molecules provide an astonishing variety of functions, like those of enzyme catalysts in biochemical reactions of live systems. The autopropagating nature of these is what life is all about.\n\nBecause of the special properties of carbon, it is likely that life on other star systems will be found to be carbon-based, in spite of speculations about the possibility of substituting silicon, which lies just below carbon in the periodic table.
771370
Mn has 25 electrons\n2, 8 , 15\nthe 15 are as 3s---2, 3p---6, rest are in 4s and 3d...(2 others)\nMn++ has thus no unpaired electron