UNIT
# 5 - COMPOUNDS
5.3 - Polar Covalent Bonding
The Hydrogen Fluoride Molecule
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This is a representation of the electron cloud about the hydrogen and fluorine atoms. The electron clouds about each atom in this molecule are not identical. The electrons are not shared equally between the two nuclei because the H atom and the F atom do not attract electrons towards their nuclei equally. The unsymmetrical distribution of the electron cloud shows that the electron cloud is distorted in the direction of the more electronegative F atom. This observed shift of electron cloud leaves the H end of the molecule slightly positive when compared to the F end. The bond that forms in the HF molecule is a polar covalent bond.
To represent an imbalanced of electron cloud, the
symbol 
is written
by the H end of the molecule to indicate that the molecule has a slightly positive
charge with respect to the F end.
The 
is written by the F end of the molecule to indicate that the molecule has a
slightly negative charge with respect to the H end.
