The oxygen end of the molecule has a partial negative charge and the hydrogen
end has a partial positive charge. This is because of the electronegativities of
the atoms O and H. O is more electronegative than H so electrons are more often
around the O atom. Electrons are negatively charged, so this causes the partial
negative charge on the O atom, similarly, the "deficiency" of electrons around
the H atoms cause partial positive charges because the nuclear charge (protons)
isn't balanced to the number of electrons around it.
Hope this helps :)
