Which of these elements is not "cooked up" by thermonuclear fusion in stellar interiors: carbon or chromium?
471954
Greetings,\n\nI would imagine they both could be depending on the size, age, and life cycle of the particular star.\n\n-matt
337972
Mostly Hydrogen.\n\nAt the center of the Sun, where its density reaches up to 150,000 kg/m3 (150 times the density of water on Earth), thermonuclear reactions (nuclear fusion) convert hydrogen into helium, releasing the energy that keeps the Sun in a state of equilibrium. About 8.9 ×1037 protons (hydrogen nuclei) are converted into helium nuclei every second, releasing energy at the matter-energy conversion rate of 4.26 million tonnes per second, 383 yottawatts (383 ×1024 W) or 9.15 ×1010 megatons of TNT per second. The fusion rate in the core is in a self-correcting equilibrium: a slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers, reducing the fusion rate and correcting the perturbation; and a slightly lower rate would cause the core to shrink slightly, increasing the fusion rate and again reverting it to its present level.\n\nHydrogen 92.1%\nHelium 7.8%\nOxygen 0.061%\nCarbon 0.030%\nNitrogen 0.0084% \nNeon o.0076%\nIron 0.0037%\nSilicon 0.0031%\nMagnesium 0.0024%\nSulfur 0.0015%
802343
The process of fusion: 4H  ----->  1He + 2positrons + neutrinoes\nwhich is:                       4p ------>  1AlphaParticle + 2 positrons\n \nie   4 protons fuse together to give an alpha particle.\n\nIt is very unlikely that 4 protons will be in the same vicinity for this reaction to occur.\n\nIn fusion reactors we use deuterium to fuse into helium.\n                  1D  +  1D    -------->   He\nas we only need two particles to collide. (This is much more likely than 4 protons colliding at once. ) \n\nOn the sun we need a way of storing the hydrogen nuclei until we have gathered 4 of them together and they can then split off as the helium nucleus.  The only store you will find on the sun is the collection of slightly heavier atomic nuclei(known by astronomers as metals and meaning any nucleus heavier than helium).\nThere are a number of pathways thought to be available for this process which proceeds through the weak nuclear reaction at a density of 1 or 2 reactions in each cubic metre of the sun. (see stellar physics books for details).  This process is the equivalent to Catalysis in ordinary chemistry.\n\nThis would be hopeless for the generation of energy in a tokamak    so we could not use this process on earth for the generation of electrical power.
517835
you mean ferrum it is nothing but the latin name of iron.\n\nIron is the most abundant metal on Earth, and is believed to be the tenth most abundant element in the universe. Iron is also the second most abundant element by mass, making up 34% of the mass of the Earth; the concentration of iron in the various layers of the Earth ranges from high (how much is "high?") at the inner core to about 5% in the outer crust. It is possible the Earth's inner core consists of a single iron crystal, although it is more likely to be a mixture of iron and nickel. The large amount of iron in the Earth is thought to create its magnetic field (you mean to say this isn't known for sure?).\n\nIron is a metal extracted from iron ore, and is almost never found in the free elemental state. In order to obtain elemental iron, the impurities must be removed by chemical reduction. Iron is used in the production of steel, an alloy or solid solution of different metals, and some non-metals, particularly carbon.\n\nNuclei of iron have some of the highest binding energies per nucleon, surpassed only by the nickel isotope 62Ni. The universally most abundant of the highly stable nucleides is, however, 56Fe. This is formed by nuclear fusion in the stars. Although a further tiny energy gain could be extracted by synthesizing 62Ni, conditions in stars are not right for this process to be favoured. When a very large star contracts at the end of its life, internal pressure and temperature rise, allowing the star to produce progressively heavier elements, despite these being less stable than the elements around mass number 60, known as the "iron group". This leads to a supernova.\n\nSome cosmological models with an open universe predict that there will be a phase where as a result of slow fusion and fission reactions, everything will become iron.
697479
Mostly hydrogen. There is a little bit of helium and heavier elements in there as well.
164903
Gravitational contraction makes things hot, just like your bicycle air pump gets hot from compressing air.  In the sun, this means TREMENDOUSLY HOT.\n\nHot enough and with enough pressure to start nuclear reactions, also facilitated by carbon atoms--the hydrogen-carbon-helium reaction:\n\nMatter is so pressed in the sun that actual space inside atoms is reduced.  Hydrogen is forced into the carbon nucleus, but it can hold only four such protons.  When this saturation state is achieved, it begins to emit helium as fast as new protons arrive.  Thus the hydrogen is changed into helium with the production of energy. Carbon, the catalyst, remains unchanged.\n\nThere is a loss of mass -- check out atomic weights and you will see a difference between two hydrogens and one helium.  The difference is mass that was converted to energy.\n\nThere are other processes going on in the sun.  Check out THE URANTIA BOOK in the 400+ pages range for more copious info on this subject in easy to understand English without jargon and pretension.\n\nThe brutally dangerous energies are attenuated by the "Compton effect" (look it up) as they percolate towards the surface transferred from one strata of elements to another.  This journey takes 500,000 years from the center!\n\nThe sun consists of many layers like an onion.  The last layer is calcium rich and 6000 miles thick.  That is because calcium is propelled to the surface, even though it is heavier.\n\nThis miraculous provision of the creators makes life possible on the earth as harmful X-rays are attenuated.\n\nCalcium is a photokinetic material under certain circumstances, where it loses one electron.  The PHOTOKINETIC FORCE propels much of this type out into the solar system annually, in spite of the massive solar gravity.\n\nYou also see shells of exploding material coming off of supernovae, much like the shell being blown off an egg.\n\nThe surface temperature of the sun is about 6000 degrees F, 3333 degrees C.\n\nHowever, in the center it is 35 million degrees Fahrenheit, about 19.4 million degrees C.\n\nThe suface is boiling.  All elements are in gaseous state, even calcium.  Much of this is boiling calcium.\n\nThere is a great battle between the forces of heat and gravity, expansion and contraction.  These have achieved a state of dynamic equilibirium on a massive scale.  At an earlier age the sun actually pulsed like those stars called Cepheid variables.\n\nI see other people have relevant details that I will not repeat.  Temperatures going out from surface are different...\n\nMy information is often left out.
889370
carbon has no free electrons available\nso it cannot conduct electricitys\nin case of germanium and si they have d orbits in the outer shell and they have greater mobility
162981
Stars use nuclear fusion to liberate the energy we perceive as light and heat.  When a star runs out of Hydrogen to fuse, it begins to fuse Helium.  This continues up the chain of elements up until Iron.  A star cannot make the jump in energy needed to go beyond this point.  With each change in fusion matter, the stars energy output increases, more heat causes the star to expand more and more.  If the star is massive enough, when it "runs out" of fuel, it will collapse upon itself in one final massive explosion of energy.  We call these Nova, or Super Nova.  The remnants of smaller Nova are Pulsars, or Neutron Stars.  The only matter left are Neutrons, no protons or electrons, no electron cloud.  Tightly packed, the material from a Neutron star is the most dense substance known.  If the star is too massive to form a Neutron star, it forms a Black Hole instead.  Stars that are not massive enough to go Nova, just burn out and cool to a brown dwarf.
897311
the lighter elements need less energy to scrap an electron from the outer shell
689695
All stars are made mostly of hydrogen, with a reasonable amount of helium thrown in for good measure.  Trace other elements exist as well, and since astronomers are so biased toward the light stuff (hydrogen and helium are the smallest atoms and therefore the lightest elements), they refer to anything heavier than helium as a “metal.”  The proportion of a star made up of stuff heavier than helium is called its “metallicity.”  The Sun’s metallicity is about 1.6% by mass.\n\nIn galactic terms, the Sun is considered “new.”  Yeah, it’s some 4.5 billion years old, but the same way anything heavier than helium gets dubbed a metal, the Sun is considered new—because it’s a second- (or maybe third-) generation star.\n\nY’see, when the Universe formed, hydrogen and helium were pretty much the only game in town, plus a bit of deuterium or lithium.  A star forming out of this stuff could have a metallicity just one millionth of the Sun’s!  To get more “metals,” the first generation of stars (i.e., the old ones) had to form, cooking up heavier elements inside their thermonuclear cores.  Some fraction of those stars went kablooie (in the form of supernovae and other exotic events), enriching the interstellar medium with heavy elements.  \n\nWhen a second (or third) generation of stars formed from this enriched interstellar medium, they had much higher metallicities.\n\nWe can find evidence for the presence of “metals” when we look at the light from individual stars or even entire galaxies.  Those elements show up as absorption features at very particular wavelengths of light, and astronomers can read that collection of “absorption lines” like a fingerprint.\n\nSo when we look at elliptical galaxies, we see evidence for very few elements heavier than helium, so we infer that the stars are “old”; when we look at most spiral galaxies, we see evidence for a metal-rich environment, so we understand the stars to be “new,” in the sense that they are second-generation stars that have benefitted from their predecessors” nuclear fusion and element production.\n\n\nRyan Wyatt\nRose Center for Earth & Space\nNew York, New York
388236
try Hydrogen, actually any thing can burn if the temperature is high enough, now consider that in a star the pressure is so high due to the immense amount of gravity that friction at the molecular level heats it up to enormous temperatures, like the core of the sun is millions of degree, that's very hot, plus in the core of most stars, there is Nuclear fusion taking place which turns the Hydrogen into Helium, it is that nuclear fusion that gives the sun and most stars all of its energy.\n\nand dont worry the sun wont run out of Hydrogen to burn for an estimated 4-5 billion years, so we'r not going to be left in the dark anytime soon.
449195
Carbon, the element, comes in three forms. These are graphite, diamond and the other (non christoline). Each is used in many ways for many things.\n\nGraphite is a flat form of carbon molecule. The cristles are hexagonal. These crystals can slide over each other acting as a lubricant. Graphite is used as a lupricant - often calles "graphite greese". It is also used in "lead" pencils.\n\nTetrahedron crystals are found in diamonds. These are not flat. These are used in jewelery, cutting tools, grinders etc. This is because diamonds are very hard and long lasting.\n\nNon crystaline carbon is used in chamical reactions. Coal is baked in baked in coke ovens to make "coke" (not the drink) which is then used in the manufacture of iron and steel.\n\nCardon is used, by plants, to make sugars, which it turn, we eat to give us energy. As our bodies "burn up" these sugars, we create carbon dioxide which we exhale.\n\nEverywhere you look you see uses of carbon - In timber, carbon fibre, Gasoline the list goes on and on.
1168125
Elements heavier than iron are produced in two ways:\n\nActually, they are ONLY produced in supernovae.  You need a huge excess of energy around because fusion of atoms into atoms heavier than iron is an endothermic reaction.  \n\nBurbridge, Burbridge, Fowler and Hoyle published the DEFINITIVE paper that illustrated why we observe elements in the proportions we do.  They used the then new understanding of nuclear chemistry (the paper published in 1957) and an estimate of energy and nucleon density in supernova explosions to reproduce the observed proportions of heavy elements.  \n\nBelow I link to a nice wiki article that describes the history of answering your question.
224377
No. In general, the inner planets of a solar system will be made up of heavy metals, while the lighter elements will be found in the outer planets. Jupiter, for example, has a core of liquid hydrogen.
300254
None of them.  \nTechnetium has been observed both in spectral star signatures, and in very small quantities in pitchblende.  To quote from Wickepedia "In 1962, technetium-99 was isolated and identified in pitchblende from the Belgian Congo in very small quantities (about 0.2 ng/kg); there it originates as a spontaneous fission product of uranium-238. This discovery was made by B.T. Kenna and P.K. Kuroda."
551989
Stars spend most of their life fusing hydrogen to helium.  As a star gets near the end of its life it starts to fuse Helium into heavier elements going up to Carbon, Oxygen, Silicon, etc (taking progressively less time to fuse each of them).\n\nEventually the star will have an Iron core but while fusing elements lighter than Iron results in an energy release trying to fuse Iron into something heavier requires energy and so the fusion reaction can not proceed any further.\n\nNow throughout the life a star the star is in a hydrostatic equilibrium between gravity pulling the star together and the radiation pressure from the nuclear fusion pushing the star apart, with the fusion reaction stopping the gravity wins and the star collapses.\n\nThe sudden collapse causes the core to be crushed to very high density at which point protons and electrons combine to form a neutron and a neutrino according to p + e -> n + ν with the neutrino escaping (the neutrinos carry most of the energy).\n\nThe core of the star is now very small and the outer layers fall in and bounce off which is what causes the explosion.\n\nIt takes a couple of hours for the outer layers of the star to actually blow apart (which is what we'd see) so the first evidence that a supernova has occured is the neutrino burst.
260144
2 H bond together to form carbon (I know that doesn't make sense due to the atomic numbers but that's right)then when all the hydrogen are gone it becomes a red giant and starts fusing carbon then when it runs out of carbon it usually explodes causing a gas of which a new star comes from