Question

Why is it important to draw a Lewis structure for a molecule before identifying the shape of a molecule?

a) To determine the number of valence electrons
b) To visualize the arrangement of atoms and electrons
c) To calculate the molecular weight
d) To identify the type of chemical bond

Answer 1

The Lewis structure is vital for visualizing the arrangement of atoms and electrons within a molecule, which informs its molecular geometry using VSEPR theory and helps identify if the molecule is polar.

Step-by-step explanation:

The importance of drawing a Lewis structure before identifying the shape of a molecule lies in the fact that the Lewis structure reveals critical information about a molecule's composition and arrangement. Specifically, the correct answer to the student's question is b) To visualize the arrangement of atoms and electrons. This is because a Lewis structure shows the number of valence electrons, how atoms are bonded, and the presence of lone pairs of electrons, which are crucial for determining the molecular geometry using VSEPR theory.

1. Determine the Lewis structure to see the atom arrangement and electron pairs.
2. Determine the number of regions of electron density around the atom using VSEPR theory.
3. Assign the set of hybridized orbitals that correspond to the geometry informed by the Lewis structure and VSEPR theory.

The drawing of the Lewis structure is the foundational step in predicting molecular structure, which includes formulating the molecular geometry and identifying whether or not the molecule is polar after assessing the symmetry of the structure.