Question

answer the questions about the following model
there are 1 reds (regions of electron density) around the central atom
a. 0 b. 1 c. 2. d. 3 e. 4
the shape at the central atom is 2
f. diatomic g. linear h. trigonal planar i. bent (120°)
j. tetrahedral k. pyramidal l. bent (109.5°)
if all of the bonds are polar covalent, is the molecule itself polar? 3
m. yes n. no

Explanation:

1. For the number of REDs:

• In VSEPR (Valence - Shell Electron - Pair Repulsion) theory, the number of regions of electron density (REDs) around the central atom is determined by the sum of the number of bonding pairs and non - bonding (lone) pairs. Looking at the model (assuming it is a common model like \(CH_4\) - type structure where there are 4 bonding pairs), the number of REDs is 4.

1. For the shape at the central atom:

• When there are 4 regions of electron density around the central atom and all are bonding pairs (no lone pairs), according to VSEPR theory, the molecular geometry is tetrahedral.

1. For molecular polarity:

• If all bonds are polar covalent but the molecule has a symmetrical shape (in this case, tetrahedral symmetry when all substituents are the same), the bond dipoles cancel out. For example, in \(CH_4\) (assuming the model is similar), although \(C - H\) bonds are polar (since \(C\) and \(H\) have different electronegativities), the tetrahedral symmetry leads to a non - polar molecule.

Answer:

1. E. 4
2. J. tetrahedral
3. N. no