Question

The bonding of chlorine with each of the Period 3 elements shows a change in bonding type from ionic through polar covalent to nonpolar covalent. Select the properties that reflect this change in bonding character.

Multiple select question.
A. Electrical conductivity at the melting point is high only for chlorides of Group 1A(1) and Group 2A(2).
B. Melting point increases as the bonding character changes from ionic to covalent.
C. At room temperature, the Period 3 covalently bonded molecules of chlorine are all liquids.
D. Electron density relief maps show a steady increase in electron sharing from NaCl to Cl2.
E. There is a general decrease in ΔEN moving from left to right across the period.

Answer 1

The change in bonding character from ionic to covalent across Period 3 when bonding with chlorine is characterized by a decrease in melting points, conductivity that is high only for more ionic compounds, and a decrease in electronegativity difference (ΔEN).

Step-by-step explanation:

The bonding character of chlorine with Period 3 elements changes from ionic to covalent as you move from left to right across the periodic table. This change is reflected in several properties:

• Electrical conductivity at the melting point is high only for chlorides of Group 1A (1) and Group 2A (2), which are more ionic.
• The melting points of chloride compounds decrease as the bonding changes from ionic to covalent, contradicting the claim that the melting point increases with such a change.
• The polarity of bonds in compounds like NaCl is high due to a large difference in electronegativity, resulting in ionic characteristics. In contrast, the covalent bonds of Cl2 are nonpolar as the difference in electronegativity is zero.
• There is indeed a general decrease in electronegativity difference (ΔEN) across the period, which is consistent with the nature of bonding changing from ionic to covalent.

Knowing that no bond is 100% ionic or covalent, the electron distribution in the bond is crucial for determining many properties of a compound. The electron density maps and percent ionic character can also provide insight into the nature of the bonds.