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is the attractive interaction hydrogen atom electrogitve atom give me a meadal
When hydrogen atoms bond covalently with highly electronegative atoms (O, F, N) its electrons are "pulled" towards the electronegative atom, causing a situation where the molecule becomes polar. Ie. in water molecules, the electronegativity of oxygen "pulls" the electrons from the hydrogen atoms toward the oxygen atom, making the ends of the hydrogen atoms furthest away from the oxygen atom relatively more positive in charge than the end of the oxygen atom furthest from the hydrogen atoms. This means that water molecules can form bonds between each other when the slightly more negative oxygen atom in one molecule is attracted to the slightly more positive hydrogen atom in another molecule. This is the cause of the high boiling temperature of water, surface tension and the fact that ice has a lower density than water.
Hydrogen bonding is in essence no different than an ordinary chemical bond. In an ordinary bond, an electron is simultaneously attracted to two nuclei, which keeps it between them. The attraction of the nuclei for the electron between them keeps the nuclei near each other -- near enough that the attraction for the electron is strong, but not so near that their mutual repulsion is strong. A hydrogen bond works the same way, except in this case the object in the middle is the proton, a positively charge beast, and the two objects attracted to it are the electron distributions on the two electronegative atoms. I realize the modern fashion is to describe the H-bond as purely electrostatic and purely classical, e.g. as just the attraction of an electropositive H atom to an electronegative F, Cl et cetera atom. But I think this is dangerously misleading. What you miss by this is the important quantum aspects of H-bonding that it shares with ordinary covalent bonding, the most important of which are that the H-bond is directional (it prefers one direction over another, which explains why H-bonded ice has the open tetrahedral structure it does), and that it is saturable, meaning once you form one H-bond between two centers, there is no inclination to form another, which helps to explain how structures held largely together by H-bonds, such as DNA, are stable.