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Polar Covalent Bonds

Polar Covalent Bonds. Trends in the Periodic Table and Bonding. -. -. -. -. +. +. +. +. Covalent Bonding. A covalent bond is a shared pair of electrons electrostatically attracted to the positive nuclei of two atoms. Both nuclei try to pull the electrons towards themselves .

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Polar Covalent Bonds

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  1. Polar Covalent Bonds Trends in the Periodic Table and Bonding

  2. - - - - + + + + Covalent Bonding A covalent bond is a shared pair of electrons electrostatically attracted to the positive nuclei of two atoms. Both nuclei try to pull the electrons towards themselves The atoms achieve a stable outer electron arrangement (a noble gas arrangement) by sharing electrons. This is like a tug-of-war where both sides are pulling on the same object. It creates a strong bond between the two atoms.

  3. Covalent Bonding Picture a tug-of-war: If both teams pull with the same force the mid-point of the rope will not move.

  4. H H e e Pure Covalent Bond This even sharing of the rope can be compared to a pure covalent bond, where the bonding pair of electrons are held at the mid-point between the nuclei of the bonding atoms.

  5. CovalentBonding What if it was an uneven tug-of-war? The team on the right are far stronger, so will pull the rope harder and the mid-point of the rope will move to the right.

  6. Polar Covalent Bond A polar covalent bond is a bond formed when the shared pair of electrons in a covalent bond are not shared equally. This is due to different elements having different electronegativities.

  7. δ- δ+ H e e I Polar Covalent Bond e.g. Hydrogen Iodide If hydrogen iodide contained a pure covalent bond, the electrons would be shared equally as shown above. This makes iodine slightly negative and hydrogen slightly positive. This is known as a dipole. However, iodine has a higher electronegativity and pulls the bonding electrons towards itself (winning the tug-of-war)

  8. δ- δ+ C Cl Electronegativities Polar Covalent Bond In general, the electrons in a covalent bond are not equally shared. e.g. 3.0 2.5 δ- indicates where the bonding electrons are most likely to be found.

  9. C Cl 2.5 3.0 P H 2.2 2.2 O H C Cl O H 3.5 2.1 P H δ- δ+ δ- δ+ Polar Covalent Bond Consider the polarities of the following bonds: Difference Electronegativities Bond 0.5 0 1.4 Increasing Polarity Complete a similar table for C-N, C-O and P-F bonds.

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