Ionic Compounds:
* Formation: Ionic compounds form when a metal (like sodium, Na) loses electrons to become a positively charged ion (cation) and a nonmetal (like chlorine, Cl) gains electrons to become a negatively charged ion (anion). The electrostatic attraction between the oppositely charged ions holds the compound together.
* NaCl: Sodium (Na) readily loses one electron to achieve a stable electron configuration, becoming Na⁺. Chlorine (Cl) readily gains one electron to achieve a stable electron configuration, becoming Cl⁻. These oppositely charged ions attract strongly, forming the ionic compound sodium chloride (NaCl).
Covalent Compounds:
* Formation: Covalent compounds form when two nonmetals share electrons to achieve a stable electron configuration.
* Cl₂: Chlorine is a nonmetal. In chlorine gas (Cl₂), two chlorine atoms each have seven valence electrons. To achieve stability, they share one electron each, forming a covalent bond.
Key Differences:
* Electronegativity: Metals have low electronegativity (attraction for electrons), while nonmetals have high electronegativity. In ionic compounds, the difference in electronegativity is large, leading to a complete transfer of electrons. In covalent compounds, the electronegativity difference is smaller, resulting in electron sharing.
* Bond Type: Ionic compounds are held together by electrostatic attraction between ions. Covalent compounds are held together by the sharing of electron pairs.
* Properties: Ionic compounds tend to have high melting points, high boiling points, and are often soluble in water. Covalent compounds generally have lower melting points and boiling points and are often insoluble in water.
In summary: The difference in bonding type between NaCl and Cl₂ stems from the electronegativity differences between the elements involved. NaCl involves a metal (sodium) and a nonmetal (chlorine), leading to ionic bonding. Cl₂ involves two nonmetals (chlorine), leading to covalent bonding.
