View Full Version : Some elements react with certain elements better than others...?
LogicalAcid
Nov16-10, 03:05 PM
Because lets say we have Hydrogen and Chlorine, they with both react very well with each other due to the reason that Hydrogen wants to get rid of its only Valence electron, to have an empty shell, and Cl needs only one more to have a full shell. Right?
No.
HCl molecule is mostly covalent, and in HCl molecule they have both full valence shells. So in this case these full valance shells are the force behind.
Your explanation would work for ionic NaCl.
espen180
Nov16-10, 03:30 PM
It's more like the ammount of energy released from having chlorine take the electron is greater that the ammount of energy lost by having hydrogen lose it. If you use a table of standard reduction potentials, you'll find that the reaction
Cl2 + H2 --> 2H+ + 2Cl-
has a Delta G value of -262 kJ, which means 262 kJ of energy is released for each mole of Cl2 which reacts.
Of course H+-cations are not stable in solution and would bind, for example to a water molecule, to form H3O+.
LogicalAcid
Nov16-10, 08:58 PM
No.
HCl molecule is mostly covalent, and in HCl molecule they have both full valence shells. So in this case these full valance shells are the force behind.
Your explanation would work for ionic NaCl.
H gave its one electron to Cl which only needed one, now they are both ions, how is this not an ionic bond?
LogicalAcid
Nov16-10, 08:59 PM
It's more like the ammount of energy released from having chlorine take the electron is greater that the ammount of energy lost by having hydrogen lose it. If you use a table of standard reduction potentials, you'll find that the reaction
Cl2 + H2 --> 2H+ + 2Cl-
has a Delta G value of -262 kJ, which means 262 kJ of energy is released for each mole of Cl2 which reacts.
Of course H+-cations are not stable in solution and would bind, for example to a water molecule, to form H3O+.
A single H+ proton is considered an atom of H?
H gave its one electron to Cl which only needed one, now they are both ions, how is this not an ionic bond?
No, as long as HCl is not dissociated in water they share two electrons. HCl is not a good example here, as it doesn't follow the obvious trends.
A single H+ proton is considered an atom of H?
No, it is not an ATOM, it is an ion (cation to be precise). But yes, single proton is considered to be a hydrogen cation.
LogicalAcid
Nov17-10, 03:12 PM
No, it is not an ATOM, it is an ion (cation to be precise). But yes, single proton is considered to be a hydrogen cation.
OK I understand, HCl is covalently bonded when not disassociated in water, but back to the question. If two elements have the exact amount of electrons one needs to lose or gain to have a full shell, they react better than ones that dont have the exact amount of electrons for both of them to have a full shell?
OK I understand, HCl is covalently bonded when not disassociated in water, but back to the question. If two elements have the exact amount of electrons one needs to lose or gain to have a full shell, they react better than ones that dont have the exact amount of electrons for both of them to have a full shell?
No, the fact that you seldomly observe a system with open shells is not that the bonds in it are less stable (or "do not form so well in a reaction" to use your diction) but that it usually will react to form even more complex compounds.
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