# stability of a negative charge in halogens and that of orbitals

when we talk about stability of halogen anions we say, $$\ce{I-} \gt \ce{Br-} \gt \ce{Cl-} \gt \ce{F-}$$, and the reason is that "the negative charge (the electrons) have more space to move about in the larger halogen". But when we talk about stability of a negative charge on an orbital, why do we say that the negative charge on the $$sp$$ hybridized orbital (which is the smaller one) is more stable than $$sp^2$$ and then $$sp^3$$ as the least stable where as the $$sp^3$$ orbital is the biggest orbital among all of the three and can allow the electrons to spread out more.

• The primary stability factor is energy. Also, what do you mean by stability, particularly what do you mean saying I- is more stable than F- ? It is easy to oxidize I-, but try it (chemically) with F-. – Poutnik Oct 5 '20 at 8:27
• I meant that the iodine anion is more stable than the flourine anion, as there is much more space for the electron density to spread out in iodine anion. @Poutnik – FinalBOSS Oct 5 '20 at 8:41
• No, that is considered reason of stability, not what you mean by stability itself. Do you mean hydrated or naked ion ? Do you mean acido-basic stability or general chemical stability ? You have put too little context in the question, what usually leads to unnecessary clarification ping-pong. – Poutnik Oct 5 '20 at 8:44
• oh that was a question on checking which compound was more acidic – FinalBOSS Oct 5 '20 at 8:57
• and that has not been included in the question, because....... ? For the basicity of hydrated halogenides part, or acidity of hydrated hydrogen halogenides, it is much more complex, as the environment interaction and thermodynamics has to be considered. See chem.libretexts.org/Bookshelves/Inorganic_Chemistry/… – Poutnik Oct 5 '20 at 9:18

• may I know why is it that "more the s character for an orbital, more is the electronegativity of it"? You have said it as bent's rule, but could you spare sometime for more explanation. The thing I am actually confused about is, people say "more is the size of an atom, the more stable it is to bear a negative charge", but doesn't it counter to say that "$sp$ orbitals which are smallest, can bear a negative charge and be stable compared to $sp^2$ and $sp^3$"? – FinalBOSS Oct 5 '20 at 15:00