Electrons are not formed in a covalent bond; instead, existing electrons within atoms are shared between them. A covalent bond is formed by the sharing of electrons between two or more atoms. These shared electrons are attracted to the positively charged nuclei of both atoms involved in the bond, effectively holding the atoms together.
Here's a breakdown:
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Electron Sharing: Covalent bonds arise when atoms share one or more pairs of electrons. This typically happens when atoms have similar electronegativities (i.e., similar abilities to attract electrons).
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Attraction to Nuclei: The shared electrons are simultaneously attracted to the positively charged nuclei of both participating atoms. This mutual attraction is the force that holds the atoms together, creating the covalent bond.
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Types of Covalent Bonds:
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Nonpolar Covalent Bonds: Electrons are shared equally between atoms. This happens when the electronegativity difference between the atoms is negligible. For example, the bond between two hydrogen atoms (H₂) is a nonpolar covalent bond.
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Polar Covalent Bonds: Electrons are shared unequally between atoms. This occurs when one atom is more electronegative than the other, meaning it has a stronger attraction for electrons. This creates a partial negative charge (δ-) on the more electronegative atom and a partial positive charge (δ+) on the less electronegative atom. A good example is the bond between hydrogen and oxygen in water (H₂O). Oxygen is more electronegative than hydrogen, so the electrons are pulled closer to the oxygen atom.
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No Electron Creation: It is crucial to understand that covalent bonding involves the rearrangement of existing electrons, not the creation of new electrons. The atoms already possess the electrons that are being shared.
In summary, electrons are not formed; they are shared between atoms to form a covalent bond due to the attraction of the shared electrons to the nuclei of both atoms. The nature of the sharing (equal or unequal) determines if the bond is polar or nonpolar.
