Question

When a carbon atom is bonded to four other atoms, what geometric arrangement occurs around the carbon atom? Why?

Short answer

When a carbon atom is bonded to four other atoms, a tetrahedral molecular geometry occurs around the carbon atom. This arrangement is a result of the repulsion of electron pairs in the sp³ hybrid orbitals of carbon and the need to minimize repulsion forces to maintain molecule stability. The bond angles of this tetrahedral geometry are approximately 109.5°.

Step-by-step solution

Understanding Carbon's Electron Configuration

Carbon has an atomic number of 6, which means it has 6 electrons. Its electron configuration can be represented as 1s² 2s² 2p². In the process of bonding with other atoms, carbon can use its two 2s and two 2p electrons to form four covalent bonds. This is known as sp³ hybridization, where the 2s and three 2p orbitals hybridize to form four sp³ hybrid orbitals.

Introducing Valence Shell Electron Pair Repulsion (VSEPR) Theory

VSEPR theory is used to predict the geometry of molecules based on the repulsion between electron pairs. According to VSEPR theory, electron pairs around a central atom will try to stay as far apart as possible to minimize repulsion forces. In this case, the carbon atom is the central atom that will form bonds with four other atoms.

Applying VSEPR Theory to Determine the Geometric Arrangement

Since carbon forms four covalent bonds in an sp³ hybridization, it will also have four electron pairs that repel each other. To minimize repulsion and maintain maximum distance between these electron pairs, they will arrange themselves in a tetrahedral manner. This results in a tetrahedral molecular geometry with bond angles of approximately 109.5°.

Why Tetrahedral Molecular Geometry Occurs

The tetrahedral molecular geometry occurs because it allows the four electron pairs around the carbon atom to stay as far apart as possible, reducing strain from repulsion forces. This geometric arrangement stabilizes the molecule and is the most energetically favorable configuration for a carbon atom bonded to four other atoms. In conclusion, when a carbon atom is bonded to four other atoms, a tetrahedral molecular geometry occurs around the carbon atom. This arrangement is due to the repulsion of electron pairs in the sp³ hybrid orbitals of carbon and the need to reduce repulsion forces to maintain stability.