= Electron transfer and ionic character
The bookkeeping steps $\mathrm{Na}\to\mathrm{Na}^++e^-$ and $\mathrm{Cl}+e^-\to\mathrm{Cl}^-$ conserve <electric charge> and describe the <Electron> inventories of separated species. They do not establish a chronological mechanism in which a labeled <Electron> jumps between two pre-existing <chemical atoms> and becomes a classical object owned exclusively by one of them. In a bound material, <quantum mechanics> determines the <electron density> and the total <energy>.
<Ionic bonding> and a <covalent bond> are useful limiting descriptions with a continuum between them. <Electronegativity> helps anticipate unequal sharing of <electron density>, but a numerical cutoff does not measure a universal fraction of <ionic bonding>. A <partial atomic charge> depends on how the <electron density> is partitioned; integer <formal charges> are a bookkeeping convention. Using $\pm e$ in a point-charge model therefore does not claim that every partition of the actual <electron density> assigns exactly those values.<The Feynman Lectures on Physics, Volume II by Richard Feynman and others>[§30–2, “Chemical bonds in crystals”: gradations between covalent and ionic bonding]{ref}<Chemistry 2e>[§7.2, “Electronegativity and Bond Type”: general guide and exceptions]{ref}
Back to article page
