Question

Use the localized electron model to describe the bonding in \(\mathrm{CCl}_{4} .\)

Short answer

The bonding in CCl4 can be described using the localized electron model as having a central carbon atom with sp3 hybridization, forming single sigma bonds with four chlorine atoms arranged tetrahedrally around it. The molecular geometry is tetrahedral with bond angles of approximately 109.5 degrees.

Step-by-step solution

Determine the total number of valence electrons in CCl4

To determine the total number of valence electrons in CCl4, we need to add the number of valence electrons of each atom. Carbon has 4 valence electrons (group 14) and chlorine has 7 valence electrons (group 17). Since there are 4 chlorine atoms, the total number of valence electrons in CCl4 is: Total valence electrons = 1 x 4 (C) + 4 x 7 (Cl) = 4 + 28 = 32 valence electrons

Draw the Lewis structure of CCl4

To draw the Lewis structure of CCl4, we need to arrange the atoms in a way that the central atom (carbon) is surrounded by 4 chlorine atoms. Carbon is the central atom because it has the least electronegative element. Then, connect each chlorine atom to the central carbon atom with single bonds. After forming these bonds, if any valence electrons remain, distribute them as lone pairs on the surrounding atoms. Finally, check if the octet rule is fulfilled for all the atoms. The Lewis structure of CCl4 is represented as follows: Cl | Cl - C - Cl | Cl In this structure, each carbon-chlorine bond consists of 2 electrons, and thus the octet rule is fulfilled for all atoms in the molecule.

Describe the electron configuration around carbon using hybridization theory

To describe the electron configuration around the central carbon atom, we must find the hybridization of the carbon atom. Carbon has four sigma bonds with four chlorine atoms in the CCl4 molecule, so it has tetrahedral electron pair geometry. This corresponds to sp3 hybridization for the central carbon atom. So, carbon has one s orbital and three p orbitals that hybridize to form four sp3 orbitals.

Explain the bond type between carbon and chlorine atoms

The bond between carbon and chlorine atoms in the CCl4 molecule is a single covalent bond formed due to the sharing of two electrons between them (one electron from the carbon atom and one electron from the chlorine atom). Thus, the C-Cl bond has a sigma bond character.

Determine the molecular geometry and bond angles

The molecular geometry of CCl4 is determined by the arrangement of the atoms in the molecule. Since carbon has four sp3 hybrid orbitals, the four chlorine atoms are arranged tetrahedrally around the central carbon atom. The bond angle between the C-Cl bonds is approximately 109.5 degrees. In conclusion, the local electron model helps describe the bonding in CCl4 as having a central carbon atom with sp3 hybridization, a single sigma bond between carbon and chlorine atoms, and a tetrahedral molecular geometry with bond angles of 109.5 degrees.

Key concepts

CCl4 Bonding

Understanding the bonding of carbon tetrachloride, or CCl4, begins with recognizing how electrons are shared between carbon and chlorine atoms. In CCl4, carbon (C) serves as the central atom with four chlorine (Cl) atoms bonded to it. This molecule is an example of covalent bonding, where electrons are shared to create stability. Each chlorine atom shares one of its electrons with carbon, which in return shares its electron, forming a single covalent bond between each C-Cl pair. Such an arrangement results in a complete octet configuration for both carbon and each chlorine atom, ensuring the overall stability of the CCl4 molecule.

Valence Electrons

Valence electrons play a vital role in determining how atoms bond together in molecules. They are the electrons in the outermost shell that are involved in chemical bonding. For CCl4, calculating the total number of valence electrons helps in drawing the molecule's Lewis structure. Carbon, which is in group 14 on the periodic table, has four valence electrons. Each chlorine atom, found in group 17, possesses seven valence electrons. As there are four chlorine atoms in CCl4, the sum of valence electrons amounts to 4 (from carbon) + 4x7 (from chlorine), equaling 32. This total number of valence electrons is used to construct the Lewis structure.

Hybridization Theory

Hybridization theory is essential to understanding why certain molecules assume their geometrical shapes. In CCl4, the carbon atom undergoes sp3 hybridization, a process that involves the mixing of one s and three p orbitals to create four equivalent sp3 hybrid orbitals. This transformation allows the central carbon to form four sigma bonds with chlorine atoms. These sp3 hybrid orbitals point toward the corners of a tetrahedron, providing a three-dimensional shape that helps explain the molecule's arrangements and angles. Such an arrangement minimizes electron-pair repulsion, contributing to the molecule's tetrahedral structure.

Sigma Bonds

Sigma bonds come into play in discussions of how atoms attach in the CCl4 molecule. These are the first type of covalent bonds to form between atoms, resulting from the head-on overlapping of orbitals. In CCl4, each sigma bond is formed by the overlap of an sp3 hybrid orbital from carbon and a p orbital from chlorine. This overlap is along the axis connecting the two atoms, which provides maximum electron density between them, ensuring a stable bond. These sigma bonds are single bonds, highlighting that each C-Cl bond consists of a pair of shared electrons, one from carbon and one from chlorine.

Molecular Geometry

The molecular geometry of CCl4 can be grasped by considering the arrangement of its atoms. Here, the geometry is characterized by the central carbon atom with four bonded chlorine atoms, all situated symmetrically around it. This symmetry and equal spacings are classics of a tetrahedral molecular geometry, where bond angles are close to 109.5 degrees. Such a shape arises because the sp3 hybrid orbitals extend outwards evenly, ensuring minimal repulsive interactions between them. The tetrahedral geometry is not just a structural feature but also contributes to the physical and chemical properties of CCl4, influencing its nonpolarity and interactions with other substances.