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The F atom is considerably larger than the H atom. Hence the compression by the lone pairs on the O atom is matched at an earlier point by repulsion between the atoms bonded to the O atom.
By "earlier point" I mean "smaller decrease from the ideal tetrahedral angle of 109.5 degrees."
well i think both are having same syr, that is pyramidal
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The arrangement of electron groups is tetrahedral, the shape of the molecule is "bent." "Pyramidal" generally refers to the shape of, e.g. ammonia.
ok i m telling my doubt that F is more EN so it attracts the electron of O rit but they had lone pair too so due to lone pair repulsion dont u think the angle of OF2 should be max while in H2O H also attract electron as it is also more EN than it also attracts electron but the angle in comparision with OF2 i think
OF2 should have max.
I am not sure what you are saying, honestly.
There are four pairs of electrons around the central O in both OF2 and H2O -- two bonding pairs and two lone pairs. Before considering anything else, we would expect those four groups to maximize the distance between them by arranging themselves at the corners of a tetrahedron. That would make the angle between the OF bonds, or between the OH bonds, equal to 109.5 degrees. It would also make the angle between the lone pairs 109.5, or the angle between either bond and a lone pair.
However, lone pairs tend to stay closer to an atom than bonding pairs, because there is no other nucleus to which they are attracted. That makes them "fatter," meaning there is a higher probability that an electron in a lone pair is found "off to the side" perpendicularly away from where the lone pair is pointing. Because they are fatter, lone pairs repel each other and bonding pairs more than bonding pairs do.
That means that we expect the fat lone pairs on the O atom to put pressure on the "skinny" bonding pairs in the OF or OH bonds, squeezing those bonding pairs closer together. And in fact, that's just what we see: the FOF and HOH bond angles are both smaller than 109.5 degrees.
However, there is an additional limit to how close the bonding pairs can be squeezed together: the repulsion between the bonded atoms -- in this case, the repulsion between the F atoms, or between the H atoms. The F atoms are much larger than the H atoms, so they repel each other more strongly.
And that means that the compression of the bond angle by the lone pairs on the oxygen is less in OF2 than it is in H2O. Hence, the bond angle in OF2 is less than 109.5, but more than the bond angle in H2O.