Correct the following statement: "The bonds in solid \(\mathrm{PbCl}_{2}\) are ionic; the bond in a HCl molecule is covalent. Thus, all of the valence electrons in \(\mathrm{PbCl}_{2}\) are located on the \(\mathrm{Cl}^{-}\) ions, and all of the valence electrons in a \(\mathrm{HCl}\) molecule are shared between the \(\mathrm{H}\) and \(\mathrm{Cl}\) atoms."

Ionic bonding occurs when atoms with significantly different electronegativities interact, resulting in the transfer of electrons from one atom to another. This creates ions; one becomes positively charged (cation) and the other negatively charged (anion). The electrostatic attraction between these oppositely charged ions forms an ionic bond. This bond is typically found between metals, like lead (Pb) in lead(II) chloride (PbCl₂), and nonmetals, such as chlorine (Cl).

For instance, in PbCl₂, each Pb atom transfers two of its valence electrons to two Cl atoms, creating a Pb²⁺ ion and two Cl⁻ ions. Contrary to the misconception that all valence electrons in an ionic compound are located on the anion, cations also contribute valence electrons during the formation of ionic bonds.

Covalent bonding is a type of chemical bond where two atoms share pairs of electrons. It commonly occurs between nonmetal atoms that have similar electronegativities. Instead of transferring electrons to form ions as in ionic bonds, the atoms in a covalent bond share electrons to achieve a full valence shell, leading to a stable electronic configuration.

In the case of an HCl molecule, hydrogen (H) and chlorine (Cl) atoms come together to share a pair of electrons – one from H and one from the outer shell of Cl. This electron sharing results in a covalent bond between the two atoms. However, not all of Cl’s valence electrons are involved in the sharing. Cl has seven valence electrons, and only one is shared with H to form the bond.

Electron transfer is a fundamental aspect of ionic bonding. It involves the movement of electrons from one atom to another, leading to the formation of ions. Atoms that lose electrons become positively charged cations, while atoms that gain electrons become negatively charged anions. The drive for electron transfer is generally the difference in electronegativities between the atoms.

In PbCl₂, the lead atom, having a lower electronegativity, loses two electrons (valence electrons) and becomes a cation (Pb²⁺). Each chlorine atom gains one of these electrons, becoming an anion (Cl⁻). The net result is a crystal lattice of Pb²⁺ and Cl⁻ ions, held together by the force of ionic bonds.

Electron sharing is the defining feature of covalent bonds, which develops when two atoms hold onto the same electrons simultaneously. This often occurs in pairs, with each shared electron pair being a single covalent bond. The important factor is that both atoms achieve greater stability via this sharing.

In the case of an HCl molecule, the hydrogen atom, having only one valence electron, shares it with a chlorine atom that needs one more electron to complete its octet. This shared pair forms a single covalent bond, which is why molecules like HCl are stable. It's essential to recognize that, while the shared electrons come from the valence shells, additional valence electrons of chlorine that are not shared with hydrogen contribute to the total electron count around the Cl atom.