Question

Compare and contrast the bonding found in the ${\mathrm{H}}_2(g)$ and $\mathrm{HF}(g)$ molecules with that found in $\mathrm{NaF}(s)$.

Short answer

In summary, H2 and HF exhibit covalent bonding with varying degrees of polarity. H2 is a non-polar covalent bond with weak bond strength, while HF is a polar covalent bond with higher bond strength due to electronegativity difference. In contrast, NaF has a strong ionic bond formed by the complete electron transfer from Na to F, creating charged ions.

Step-by-step solution

Understand Covalent Bonding

Covalent bonding is a type of chemical bonding where atoms share one or more pairs of electrons. This occurs between two non-metal atoms, such as hydrogen or fluorine. In a covalent bond, both atoms contribute equally to the shared electron pair. Existence of covalent bonding can be seen in H2 and HF molecules.

Understand Ionic Bonding

Ionic bonding is a type of chemical bonding where one or more electrons are transferred from one atom to another. In an ionic compound, one atom donates electrons (forming a positive ion or cation) while the other atom gains electrons (forming a negative ion or anion). Ionic bonding occurs between a metal and a non-metal, such as sodium (Na) and fluorine (F) in NaF.

Bond Strength

Covalent bonds tend to have varying bond strengths depending on the atoms involved, while ionic bonds are generally stronger due to electrostatic attraction between oppositely charged ions. In the case of H2, its bond is fairly weak due to the small size and low electronegativity of hydrogen atoms. In contrast, HF has a much stronger bond because of the high electronegativity of fluorine. NaF has a very strong ionic bond due to the charge difference between the Na+ and F- ions.

Electron Sharing and Polarity

In a covalent bond, electrons are shared between atoms, and in an ionic bond, electrons are transferred from one atom to another. The degree of electron sharing varies in covalent bonds depending on the electronegativity difference between the atoms involved. In H2, the electrons are shared equally between the two hydrogen atoms, making it a non-polar molecule. In HF, the electron pair is more attracted to the highly electronegative fluorine, making it a polar molecule with a dipole moment. In NaF, a complete electron transfer occurs, leading to the formation of charged ions forming an ionic bond.

Bonding Comparison

In summary, the bonding in H2 and HF molecules involves covalent bonds, with varying degrees of polarity. H2 is a non-polar covalent bond with weak bond strength, while HF is a polar covalent bond with higher bond strength due to electronegativity difference. On the other hand, NaF has a strong ionic bonding formed due to the complete electron transfer from Na to F creating charged ions.

Key concepts

Covalent Bonding

Covalent bonding is fundamental in the realm of chemistry, where atoms come together by sharing electrons to achieve greater stability. In essence, it's like a partnership where each non-metal atom brings one or more electrons to the table, creating a stable electronic configuration reminiscent of noble gases.