For an atom to be partially charged means it carries a non-integer electric charge that is less than a full elementary charge. This occurs because of an unequal distribution of electrons in chemical bonds, where electrons are not shared equally between atoms due to differences in electronegativity. As a result, one atom in a bond has a slight excess of negative charge (partial negative charge, δ-) while the other has a slight deficiency (partial positive charge, δ+). These partial charges represent a shift in electron density around the atoms rather than full ionic charges, reflecting a polar covalent bonding situation rather than a complete transfer of electrons as in ionic bonds.
In essence, a partially charged atom is one where electron density is polarized, creating regions within the molecule that have slight positive and negative charges, which influence the molecule's reactivity and interactions with other molecules.
