Melting and Boiling clues of Hydrogen Fluoride (HF) are greater than Hydrochloric acid (HCl), Hydrobromic acid (HBr) and Hydrogen iodide (HI).
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Fluorine has the highest electronegativity of one atom. As soon as fluorine bonds with hydrogen, the polarity is so strong that it begins to exhibit the residential property of hydrogen bonding, which is in concentrate just an extreme dipole. Chlorine just doesn’t have the pull of that is halogen counterpart and also can’t kind that polar of a molecule.
According come Fajan’s dominance with the rise of the dimension of anions, the tendency to be polarized increases. Because, as the size of anion increases, the distance between its nucleus and also outermost electron increases and hence the cell nucleus can attract the electron less. Therefore the cation can more easily deform the anion. Therefore in any kind of group in the routine table the tendency of the anion to be polarized rises from height to bottom. Because that example, the radii the the halide ions room as follows.
F– (1.33A) – (1.81A) HCl > HBr > HI
Again, as result of the existence of hydrogen binding in Hydrogen Fluoride (HF) molecule, it’s melting and boiling points room higher. Fluorine has a higher electronegativity than the various other halogens which method for fluorine it undergoes hydrogen bonding which offers it a boiling point of about 19 degrees Celcius. Conversely, hydrogen chloride boils in ~ -80.05 levels Celcius. The various other halogens being much less electronegative 보다 Fluorine would therefore not type hydrogen bonds come a level that fluorine does.
Hence the intermolecular force between the molecule of HF compound rises which causes higher melting and also boiling points. But in the case of HCl, HBr, and HI, they can’t kind a hydrogen bond. Thus their melting and also boiling point out are lower than HF.
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Due to the high electronegativity that fluorine hydrogen bonds deserve to be formed in between HF molecules. Hydrogen bonds require more energy to break the London Forces. The various other halogens room not as electronegative and also so other hydrogen halides cannot form hydrogen bonds in between molecules. Therefore an ext energy is required to rest the intermolecular pressures in HF than the various other hydrogen halides and so it has actually a higher boiling point. Stronger hydrogen bonding leads to a greater boiling point. As such you have actually a greater charge difference in between the hydrogen atom and the fluoride atom bring about a better attraction and also strongness of the hydrogen bonding.