# Predict the molecular shape of methane

Predict the molecular shape of methane, the carbonate ion, carbon dioxide, and the sulfite ion. ## General guidance

Concepts and reason
This problem is based on the concept of chemical bonding. VBT and VSEPR deal only with sigma bonds and valence electrons. There is no requirement of pi-bond in the process of determining the molecular shape.

Fundamentals

Theories such as VBT (valence bond theory) and VSEPR (valence shell electron pair repulsion theory) help in determining the shape, geometry and hybridization of a particular compound on the basis of various factors like valence bond, valence electrons and lone pairs.

## Step-by-step

### Step 1 of 8

Methane: In case of methane molecule, the steric number is four in which the number of sigma bonds is 4 and number of lone pair of electrons at central atom is zero. Thus, bent, trigonal pyramidal, trigonal planar and linear molecular shapes are not possible.

Steric number is the sum of number of sigma bonds and number of lone pair of electrons. So, for methane molecule the steric number is 4 as the number of sigma bonds is 4 and the number of lone pair in the structure is 0.

### Step 2 of 8

The molecular shape of the methane is given below: The molecular shape of the methane molecule is tetrahedral.

Steric number and hybridization of methane is 4 and . Thus, the molecular shape of methane will be tetrahedral.

### Step 3 of 8

Carbonate ion: In case of carbonate molecule, the steric number is 3 in which the number of sigma bonds is 3 and number of lone pair of electrons at central atom is zero. Thus, bent, trigonal pyramidal, linear and tetrahedral molecular shapes are not possible.

Steric number is the sum of number of sigma bonds and number of lone pair of electrons. So, for carbonate the steric number is 3 as the number of sigma bonds is 3 and the number of lone pair at central atom in the structure is 0.

### Step 4 of 8

The molecular shape of carbonate is given below: The molecular shape of the carbonate molecule is trigonal planar.

Steric number and hybridization of carbonate is 3 and . Thus, the molecular shape of carbonate will be linear.

### Step 5 of 8

Carbon dioxide: In case of carbon di oxide molecule, the steric number is 2 in which the number of sigma bonds is 2 and number of lone pair of electrons at central atom is zero. Thus, bent, trigonal pyramidal, trigonal planar and tetrahedral molecular shapes are not possible.

Steric number is the sum of number of sigma bonds and number of lone pair of electrons. So, for carbon di oxide the steric number is 2 as the number of sigma bonds is 2 and the number of lone pair at central atom in the structure is 0.

### Step 6 of 8

The molecular shape of carbon di oxide is given below: The molecular shape of the carbon di oxide molecule is linear.

Steric number and hybridization of carbon di oxide is 2 and . Thus, the molecular shape of carbon di oxide will be linear.

### Step 7 of 8

Sulfite ion: In case of sulfite molecule, the steric number is 3 in which the number of sigma bonds is 3 and number of lone pair of electrons at central atom is zero. Thus, bent, trigonal planar, linear and tetrahedral molecular shapes are not possible.

Steric number is the sum of number of sigma bonds and number of lone pair of electrons. So, for sulfite the steric number is 4 as the number of sigma bonds is 3 and the number of lone pair at central atom in the structure is 1.

### Step 8 of 8

The molecular shape of sulfite is given below: The molecular shape of the sulfite ion molecule is trigonal pyramidal.

Steric number and hybridization of sulfite is 4 and . Thus, the molecular shape of sulfite will be trigonal pyramidal.