How to Draw the Lewis Dot Structure for NH4+ and Determine Its Shape and Polarity

a) Draw the Lewis Dot Structure for NH4+:

To draw the Lewis dot structure for NH4+ (ammonium ion), follow these steps:

1. Count the total number of valence electrons: Nitrogen (N) has 5 valence electrons, and each Hydrogen (H) has 1 valence electron. Since NH4+ has a +1 charge, we subtract 1 electron. So, the total number of valence electrons is 5 + (4 × 1) – 1 = 8.
2. Place the Nitrogen atom in the center and arrange the four Hydrogen atoms around it.
3. Draw single bonds between the Nitrogen atom and each Hydrogen atom. This uses up 8 electrons (4 bonds × 2 electrons each).
4. Since all electrons are used in bonding, there are no lone pairs on the Nitrogen atom.

b) Draw a Second Structure with Bonds Drawn:

The second structure is essentially the same as the first, but with the bonds explicitly drawn as lines:

    H
    |
H—N—H
    |
    H

c) Determine the Shape Using VSEPR Theory:

According to VSEPR (Valence Shell Electron Pair Repulsion) theory, the shape of NH4+ is determined by the number of electron pairs around the central atom. In NH4+, there are 4 bonding pairs and no lone pairs. This results in a tetrahedral shape, with bond angles of approximately 109.5°.

d) Determine if the Molecule is Polar or Nonpolar:

NH4+ is a nonpolar molecule. Although the N-H bonds are polar, the tetrahedral shape of the molecule means that the dipole moments of the individual bonds cancel each other out, resulting in no net dipole moment for the molecule as a whole.