Qube
Gold Member
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Does the polarity of the binary halogen acids increase or decrease down the group?
I have one argument for decrease based solely on electronegativity considerations.
I have one argument for increase based on orbital overlap and electron density. Taking electron density in an orbital to be non-uniform and decreasing as we get further from the nucleus, it follows that as the halogens get bigger, there is less electron density at the fringes - or where the hydrogen would overlap. This, combined with the relatively greater electronegativity of the halogens (expect iodine) relative to hydrogen, gives the bond ionic character.
Which one is correct?
I have one argument for decrease based solely on electronegativity considerations.
I have one argument for increase based on orbital overlap and electron density. Taking electron density in an orbital to be non-uniform and decreasing as we get further from the nucleus, it follows that as the halogens get bigger, there is less electron density at the fringes - or where the hydrogen would overlap. This, combined with the relatively greater electronegativity of the halogens (expect iodine) relative to hydrogen, gives the bond ionic character.
Which one is correct?