Covalent Bond
Definition:
A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons. This sharing allows each atom to achieve a more stable electron configuration, often filling their outer electron shells.
How It Works:
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Atoms tend to be more stable when their outermost electron shells are full (following the octet rule for many elements).
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Instead of transferring electrons (as in ionic bonds), covalent bonding involves atoms sharing electrons.
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The shared electrons belong to both atoms simultaneously, creating a strong bond between them.
Types of Covalent Bonds:
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Single bond: one pair of shared electrons (e.g., H—H in hydrogen gas).
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Double bond: two pairs of shared electrons (e.g., O=O in oxygen gas).
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Triple bond: three pairs of shared electrons (e.g., N≡N in nitrogen gas).
Properties of Covalent Bonds:
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Typically form between non-metal atoms.
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Molecules with covalent bonds can be gases, liquids, or solids.
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Covalent compounds often have lower melting and boiling points compared to ionic compounds.
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They do not conduct electricity in solid or liquid states because there are no free ions or electrons.
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Covalent bonds can be polar (unequal sharing) or nonpolar (equal sharing), depending on the electronegativity difference between atoms.
Importance:
Covalent bonding is fundamental in chemistry, forming the basis of molecules in organic compounds, biological macromolecules (like DNA, proteins), and many materials.