Question

The bonds between \(\mathrm{P}\) atoms and \(\mathrm{Cl}\) atoms in \(\mathrm{P} \mathrm{Cl}_{5}\) are likely to be (1) ionic with no covalent character (2) covalent with some ionic character (3) covalent with no ionic character (4) ionic with some metallic character

Short answer

Option (2): covalent with some ionic character

Step-by-step solution

- Identify the type of bonding

Consider the elements involved, Phosphorus (P) and Chlorine (Cl). Both are nonmetals, which typically form covalent bonds.

- Analyze the electronegativity

Phosphorus and Chlorine have different electronegativities, with Chlorine being more electronegative. This means that while the bond is mainly covalent, there can be some ionic character due to the difference in electronegativity.

- Ruling out other options

Since both atoms involved are nonmetals, options involving ionic or metallic characteristics as the primary bond type are not applicable.

- Conclusion

Given a covalent bond with differing electronegativities of the atoms, the bonds in \(\text{PCl}_5\) are most aptly described as covalent with some ionic character.

Key concepts

Covalent Bond

A covalent bond is a type of chemical bond where atoms share electrons. This bond typically occurs between nonmetal atoms. In the case of \(\text{PCl}_5\), both Phosphorus (P) and Chlorine (Cl) are nonmetals. When two nonmetals bond, they tend to share their valence electrons to achieve a full outer shell, resembling the electron configuration of noble gases.

Covalent bonds can be classified into single, double, or triple bonds, depending on the number of shared electron pairs. Additionally, covalent bonds can sometimes exhibit polarity, meaning that the shared electrons are not equally distributed between the atoms involved. This will be discussed in the electronegativity section.

Ionic Character

While covalent bonds involve the sharing of electrons, some covalent bonds can have ionic character. Ionic character refers to the degree to which the electrons are not equally shared between the atoms. This happens when there is a significant difference in the electronegativities of the bonded atoms.

In \(\text{PCl}_5\), Chlorine is more electronegative than Phosphorus, meaning Chlorine attracts the shared electrons more strongly. This difference creates a partial negative charge on the Chlorine atoms and a partial positive charge on the Phosphorus atom, giving the bond some ionic character.

• Covalent bonds with significant ionic character can have physical properties that are intermediate between purely covalent and purely ionic compounds.

Electronegativity Difference

Electronegativity is the tendency of an atom to attract electrons in a chemical bond. When two atoms have different electronegativities, the electrons in the bond are pulled more towards the more electronegative atom.

This difference in electronegativity creates a separation of charges and results in partial ionic character even within a predominantly covalent bond.
In \(\text{PCl}_5\), Phosphorus has an electronegativity of around 2.19, while Chlorine has an electronegativity of about 3.16. This difference leads to electron density being unevenly distributed, making the bonds have some ionic character despite being largely covalent.

Nonmetals

Nonmetals are elements primarily found on the right side of the periodic table. They tend to have high electronegativity and ionization energy values.

Nonmetals readily form covalent bonds by sharing electrons and are key components in many molecular compounds.
Examples of nonmetals include hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and halogens like fluorine and chlorine.
In the context of \(\text{PCl}_5\), both Phosphorus and Chlorine are nonmetals. Their bonding is predominantly covalent with some ionic character due to their difference in electronegativities.

• This shows the significant role nonmetals play in determining the type and nature of bonding in compounds.