[عاطف خليفة]

* HYDROGEN BOND

Aris when the hydrogen atom locates between two atoms their electron negatvity lnigls slighlly then the electrons negatwily of hydrogen atom

1- Hydrogen atom acts as a bridge between two atoms of high electronegativity, So the molecules get near to each other(bonded together)

2- Ex. Water:-
It is a polar molecule.
The hydrogen atom bonds between two atoms of oxygen (Electronegativity of hydrogen 2.1. and that of oxygen = 3.5)
In water oxygen carries a partial negative charge and hydrogen carries a partial positive charge.

3- Properties:
a) It is longer but less strength than covalent bond
b) The strength increase as the electronegativity of bonded atoms increases
c) It needs high temperature to break down the bond sothe boiling point and melting point are high.
D) Forms of hydrogen bonds
(1) straight line
(2) Closed ring.
(3) Open net