DIPOLE MOMENT. Electronegativity Polarity of Bonds Dipole Moment Dipole Moment of Polar Covalent Bond Dipole Moment of Non Polar Covalent Bond Example of Dipole Moment. Next. ELECTRONEGATIVITY.
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Polarity of Bonds
Dipole Moment of Polar Covalent Bond
Dipole Moment of Non Polar Covalent Bond
Example of Dipole Moment
Definition: Electronegativity is chemical property that describes the ability of an atom to attract electron towards itself in a covalent bond.
Trends In Electronegativity:
Electronegativity increases across the period.
Decrease down the group.
Fluorine is most electronegative element.
Cesium is least electronegative element.
Exceptions: Gallium and Germanium have higher electronegative than Aluminum and Silicon respectively because of the D-block contradiction.
Order In Decreasing Electronegativity:
Definition: When there is a bond between atom with (difference< 1.7) different electronegativity , then more electronegative atoms has a partial negative charge, and other has a partial positive charge, resulting a formation of Polar Covalent Bond.
Polar Molecules: A molecule is polar when their exists two separate poles of charges in the molecules at two different positions.
Example of Polar Molecules: H2O, HCL, NH3,SO2 etc.
Non –Polar Molecules: Those molecules in which there is no charge separation of positive and negative charges in a molecule and such a resultant molecule is neutral.
Example of Non Polar Molecules: Co2, BF3, BeH2, CH4 etc.
When a bond is formed between two dis-similar atoms, then more electronegative element becomes more electron rich whereas the less electronegative element becomes electron deficient, resulting a polar Covalent Bond.
The dipole moment of polar bond is non-zero and is represented as Цbond ≠ 0
The dipole moment of polar molecules is non- zero.
When a bond id formed between two similar atoms with similar electronegativity, then bond pair of electrons is equally attracted by both the atoms. As e result both the atoms are neutral.Such a bond formed is Non-Polar Covalent Bond.
The dipole moment id non- polar bond is zero and is represented as
The resultant dipole moment of a non- polar molecule is zero and is represented as цmolecule =0.
H2O (Water): In Case of water, there are two bonds each one is polar. We can get the resultant of both O-H bonds is in upward direction by adding vector ally. Additionally, the one pairs increase the molecular dipole since they consists of significant negative ion construction. So we call water a polar molecule because it has a molecular dipole.
BeCl2: In Case of BeCl2, two polar bonds at 180 degree from each other and of the same magnitude. Thus, they cancel each other. So molecule is non- polar even though the bond is polar.
BF3: In BF3, three bond dipoles and each at 120 degree from each other. These add vectorially in such a way as to cancel each other out. So, the molecule is non- polar.
CH4: In Methane molecule, there are 4- polar bonds oriented at the tetrahedral angle of 109.5 degree from each other and these form bond dipoles cancel out each other. So this molecule is non- polar.
PCL5: In Phosphorus pentachloride, the 3 equatorial bond cancels out each other dipole moment and axial bonds are at 180 degree to each other and cancel Out. So, molecule is non- polar.