How is the tetrahedral shape determined in methane?

The tetrahedral shape in methane is determined by the repulsion between the four pairs of bonding electrons around the carbon atom.

In methane (CH4), the central carbon atom is bonded to four hydrogen atoms. The carbon atom has four valence electrons, each of which forms a covalent bond with a hydrogen atom. The hydrogen atoms contribute one electron each, resulting in four pairs of bonding electrons around the carbon atom. According to the Valence Shell Electron Pair Repulsion (VSEPR) theory, these electron pairs will arrange themselves to be as far apart as possible to minimise repulsion. This results in a tetrahedral shape, with bond angles of approximately 109.5 degrees.

The VSEPR theory is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. It is based on the idea that pairs of electrons occupy space around an atom and will arrange themselves to minimise repulsion, thus determining the shape of the molecule. In the case of methane, the four pairs of bonding electrons around the carbon atom are arranged in a tetrahedral shape to minimise repulsion.

The tetrahedral shape is one of the most common molecular geometries in chemistry, especially for molecules with a single central atom. It is characterised by four atoms or groups of atoms arranged at the corners of a tetrahedron with the central atom in the middle. This shape allows for the maximum separation between the electron pairs, reducing the repulsion between them and making the molecule more stable.

In conclusion, the tetrahedral shape in methane is determined by the repulsion between the four pairs of bonding electrons around the carbon atom. This is in line with the VSEPR theory, which predicts the geometry of molecules based on the number of electron pairs surrounding their central atoms.