which atom can have an expanded octet? P, C, N, or H,?
362520
P, expanded octets dont happen to atoms in the first or second rows.
715300
Carbon has 4 valence electrons. To form an octet (8 electrons), it has to\n\n1) form 4 single bonds (receive 1 sharing electron from each bond with another element), or\n\n2) form 2 double bonds (receive 2 sharing electrons from each bond), or\n\n3) form 1 triple bond (receive 3 sharing electrons) and 1 single bond (receive 1 sharing electrons).\n\nDepending what element that C is bonding to, any one of the above situation can happen.
150155
Carbon bound to Nitrogen by a triple bond.
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.
365377
atomic number represents the number of protons or electrons in an atom
649511
A carbon atom is one that has 6 proton in the nucleus. If it is uncharged, there will also be 6 electrons. The number of neutrons varies depending on the isotope. The most common isotope has 6 neutrons. There is another stable isotope with 7 neutrons and a radioactive one with 8.
298477
neutrons\n\nIsotopes have to have the same numbers of protons\nor they'd be different elements.  Since the\nelectrons match up with the protons, the electron\ncount is consistent too.
72779
A molecule is made up of atoms.
673864
http://en.wikipedia.org/wiki/Pi%C3%B1ata
668052
The octet rule is a simple chemical theory that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, similar to the electronic configuration of a noble gas. The theory is applied to the main-group elements, especially carbon, nitrogen, oxygen, and the halogens. In simple terms, molecules are more stable when the outer shells of their constituent atoms are empty or full, that is, have 8 electrons in the outer shell. See electron shells.\n\nThe octet rule also states that atoms react generally by gaining, losing, or sharing electrons in order to achieve a complete octet of 8 valance electrons. An octet of electrons results in a very stable electron configuration. This stability is the reason that the noble gases are so unreactive. This combination occurs primarily in two ways, electrovalent bonding and covalent bonding.
980851
C, having both positive and negative charges on one molecule.
832259
N cannot expand its outer level to more than 8 electrons, because it is in Period 2.  NF5 would require there to be 10 electrons in the outer level of N.
76628
By "shells," do you mean the energy levels of the electron orbitals?  If that's what you mean, all you do is look on the period table and count how many rows from the top the element is.  So H and He each have one electron shell, C, N, O, F, etc. all have two, Si, B, Na, Cl, etc. all have three, and so on.  Sorry about the scattered examples (I was listing them by memory), but hopefully you get the idea.
859468
Elements are Carbon, Nitrogen, Phosphate, Oxygen
156923
I don't know if this would be possible. The C atom is able to acheive this state, which is semi-unique to the group IV atoms such as Si, Ge, Pb, and Sn. \n\nFor a hydrogen atom to acheive sp2 hybridization it would have to skip 4 base states. This configuration is 'highly' improbable and would be 'highly' unstable requiring a steady influx of energy to retain this configuration.
746884
if we use carbon as the example-there are four electron in the outer shell.  these would normally consist of one s shell electron and 3 p shell electrons.  instead of doing that, the 4 electrons become hybrids in that they all act the same and take on some s shell and some p shell character, so instead of having 1 and 3 of s and p type, you end up with 4 electrons of sp shell.\n\nif you kept the 1-s and 3-p configuration, the s would act one way and the p's would act another.  since they all become sp electrons, they act the same way, so in the case of something like methane (CH4), each of the hydrogens are equally spaced away from each other, kind of looking like a pyramid (they each are 109.5 degrees away from each other)
1024924
Well, there's been much speculation whether another element would be able to be the "base" for a life form. Silicon is indeed one theory. However, I have also heard speculation that life without carbon is impossible. \n\n   Carbon is probably the most versatile element there is. There is an infinite variety and number of life forms that could be made out of it. It's structure allows many shapes of carbon to form, rings, and chains, and more, and it allows lots different molecules and elements to hook on to the structure. Seeing as all life forms i know of are formed out of only Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and sulpher, the ability to make proteins, carbohydrates, nucleic acids and fats out of these elements is essential, and something like silicon probably wouldn't do it.