Polar covalent bond

A covalent bond in which shared electrons are distributed unequally, leaving the bonded atoms with partial opposite charges.

Electronegativity: A measure of an atom’s tendency to attract shared electrons in a chemical bond. Differences in electronegativity predict which atom gains greater electron density.
Electron: A negatively charged subatomic particle that occupies atomic orbitals and participates in chemical bonding. The shared particles whose distribution becomes unequal are electrons.
Molecular polarity: The uneven distribution of electric charge across an entire molecule. Bond dipoles contribute to molecular polarity, though molecular geometry can cancel them.
Nonpolar covalent bond: A covalent bond in which shared electrons are distributed equally or nearly equally. It is the low-polarity counterpart, with little or no bond dipole.
Bond dipole moment: A vector measure of charge separation across a chemical bond. Unequal electron sharing produces the dipole measured by this quantity.
Chemical bond: An interaction that holds atoms or ions together in a chemical substance. Polar covalent bonding is one specific way atoms are held together.
Water: A molecule composed of two hydrogen atoms bonded to one oxygen atom. Its polar O–H bonds and bent shape give it a permanent molecular dipole.
Ionicity: The degree to which a chemical bond has ionic rather than covalent character. Real bonds span a continuum between electron sharing and charge separation.
Partial charge: A fractional positive or negative charge assigned to an atom within a molecule. The unequal sharing leaves one bonded atom δ− and the other δ+.
Valence electron: An electron in an atom’s outer shell that can participate in chemical bonding. Covalent bonds share valence electrons between bonded atoms.

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