Question

Among the following compounds the one that is polar and has the central atom with sp² hybridization is (a) \(\mathrm{H}_{2} \mathrm{CO}_{3}\) (b) \(\mathrm{SiF}_{4}\) (c) \(\mathrm{BF}_{3}\) (d) \(\mathrm{HClO}_{2}\)

Short answer

The compound that is polar and has sp² hybridization is \\(\mathrm{HClO}_2\\).

Step-by-step solution

Understand Polarity

A compound is polar if it has a net dipole moment. This occurs when there is an uneven distribution of electron density, often due to differences in electronegativity and the geometry of the molecule.

Determine Hybridization

The type of hybridization can be determined by examining the steric number, which is the sum of the number of atoms bonded to the central atom and the number of lone pairs on the central atom.

Analyze Each Option

Evaluate each compound: (a) \(\text{H}_2\text{CO}_3\) - Central atom (C) with potential for sp² (trigonal planar, but requires checking polarity).(b) \(\text{SiF}_4\) - Si is surrounded by 4 F atoms, indicating sp³ hybridization (tetrahedral, non-polar).(c) \(\text{BF}_3\) - B is bonded to 3 F atoms, which indicates sp² hybridization (trigonal planar, non-polar because symmetric dipoles cancel).(d) \(\text{HClO}_2\) - Central atom (Cl) with potentially sp² hybridization due to binding configuration and presence of lone pairs.

Check Polarity of Each Option

(a) \(\text{H}_2\text{CO}_3\) may be polar based on structure; needs confirmation.(b) \(\text{SiF}_4\) is non-polar as the dipoles cancel out.(c) \(\text{BF}_3\) is non-polar because the molecular shape allows dipoles to cancel completely.(d) \(\text{HClO}_2\) is polar due to the presence of lone pairs on Cl, which causes asymmetric geometry and an overall dipole moment.

Conclusion

The compound that is polar and has sp² hybridization at the central atom is \(\text{HClO}_2\) due to its molecular geometry and presence of electron lone pairs causing a net dipole moment.

Key concepts

Polarity of Molecules

Molecular polarity is all about how the electrons are distributed in a molecule. When the distribution of electrons is uneven, the molecule becomes polar, meaning it has a positive and a negative side. This often happens in molecules where the atoms have different electronegativities, which means they "pull" on electrons with different strengths.

Polarity is strongly influenced by the shape of the molecule. Even if a molecule has polar bonds, it can still be non-polar if its shape allows those polarities to cancel out. For example, in linear or symmetric compounds, the dipoles may balance each other, resulting in a non-polar molecule.

If you're examining whether a molecule is polar, you should consider:

• The electronegativity difference between atoms
• The symmetry and shape of the molecule
• The presence of lone pairs that can create an uneven distribution of electrons

Understanding these factors helps predict whether a molecule is polar or non-polar.

Hybridization in Chemistry

Hybridization in chemistry explains how atomic orbitals mix to form new hybrid orbitals. This concept helps us understand the bond formation and the 3D shapes of molecules. When atoms bond, their atomic orbitals combine to form hybrid orbitals in order to maximize the overlap and minimize the energy of the molecule.

The type of hybridization depends on the number of regions of electron density around a central atom. This is calculated using the steric number, which is the sum of bonded atoms and lone pairs around the central atom. Here are some common hybridizations:

• sp: Two regions of electron density, linear shape
• sp²: Three regions of electron density, trigonal planar shape
• sp³: Four regions of electron density, tetrahedral shape

For example, in \(\text{HClO}_2\), chlorine has a steric number of three due to its bonding and lone pairs, resulting in sp² hybridization. This concept is key in predicting molecule shapes and understanding their chemical behavior.

Dipole Moment in Chemical Compounds

The dipole moment is a measure of a molecule's overall polarity and is indicated by a vector pointing from the positive to the negative end of a molecule. This vector originates from differences in electronegativity between atoms, leading to an uneven sharing of electrons.

For a molecule to have a dipole moment, it must have both polar bonds and an asymmetrical shape. This ensures that the vectors pointing in different directions don't cancel each other out completely. For instance, in water (H₂O), the bent shape prevents the two dipole moments of the O-H bonds from cancelling, resulting in a net dipole moment.

Factors that influence dipole moments include:

• Differences in electronegativity between bonded atoms
• The molecular geometry, especially the symmetry
• The presence of lone pairs causing asymmetrical shapes

Understanding dipole moments allows chemists to predict the behavior of molecules in different contexts, such as solubility in different solvents or reactivity.