Question

Draw the Lewis structure for the \(\mathrm{NH}_{4}+\) ion.

Short answer

The Lewis structure for the \(\mathrm{NH}_{4}+\) ion has a central nitrogen atom connected to four hydrogen atoms by single bonds, with no remaining lone pairs. The formal charge on the nitrogen atom is +1, and the overall charge of the ion is also +1.

Step-by-step solution

Count the total number of valence electrons

In the \(\mathrm{NH}_{4}+\) ion, there is one nitrogen atom and four hydrogen atoms. Nitrogen has 5 valence electrons, and hydrogen has 1 valence electron. However, since the ion has a charge of +1, we need to subtract one electron from the total count. So, the total number of valence electrons available is: Total valence electrons = (1 nitrogen x 5) + (4 hydrogen x 1) - 1 (charge) = 5 + 4 - 1 = 8 electrons.

Connect the atoms with single bonds

Draw a single bond between the nitrogen atom and each hydrogen atom. These 4 single bonds utilize 8 electrons (2 electrons per single bond).

Distribute the remaining valence electrons

There are no remaining valence electrons after connecting the central nitrogen atom to the 4 hydrogen atoms with single bonds.

Check the formal charge on each atom

The formal charge on an atom can be calculated using the following formula: Formal charge = (number of valence electrons) - (number of bonds) - (number of non-bonding electrons) In our case, the formal charge on nitrogen is: Formal charge on N = (5 valence electrons) - (4 bonds) - (0 non-bonding electrons) = +1 The formal charge on each hydrogen atom is: Formal charge on H = (1 valence electron) - (1 bond) - (0 non-bonding electrons) = 0 The overall charge on the \(\mathrm{NH}_{4}+\) ion is: Overall charge = (+1 charge on nitrogen) + (4 hydrogen x 0 charge on each) = +1 This matches the given charge of the ion. Therefore, the Lewis structure for the \(\mathrm{NH}_{4}+\) ion would have a central nitrogen atom connected to four hydrogen atoms, with no remaining lone pairs. The formal charge on the nitrogen atom is +1, and the overall charge of the ion is also +1.

Key concepts

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding. They play a crucial role in determining the chemical properties and reactivity of an element. In the case of drawing Lewis structures, understanding valence electrons is fundamental.

For example, in the provided exercise, nitrogen has 5 valence electrons, and hydrogen has 1. These electrons are what atoms use to form bonds with each other. When calculating the total number of valence electrons for the (H_{4}^+) ion, we must account for the positive charge, which indicates a loss of one valence electron from the system, leading to a total of 8 valence electrons that are used to form bonds and complete the octet for the nitrogen atom.

Formal Charge

The concept of formal charge is essential in understanding how atoms share their electrons in molecules and ions. It's a theoretical charge calculated based on the electron ownership assumption, where bonding electrons are equally shared between the bonded atoms.

The formula to calculate the formal charge is: Formal charge = (number of valence electrons on the free atom) - (number of bonds) - (number of non-bonding electrons)By applying this formula to the nitrogen atom in the (H_{4}^+) ion, we subtract the number of bonds (4) from the number of valence electrons (5) that nitrogen would have in its neutral state, revealing a formal charge of +1. Each hydrogen atom has a formal charge of 0. Confirming that the sum of the formal charges equals the overall charge of the ion is vital for ensuring the correctness of a Lewis structure.

Chemical Bonding

Chemical bonding is the process by which atoms combine to form compounds. There are several types of bonds, including ionic, covalent, and metallic bonds. In our exercise, the focus is on covalent bonding, where atoms share valence electrons to achieve a full outer electron shell.

In the (H_{4}^+) ion, the bonding between the nitrogen and the hydrogen atoms is purely covalent. Each single bond represents a pair of shared electrons, allowing the atoms to reach a more stable electronic configuration. In Lewis structures, lines represent these shared pairs of electrons, and in (H_{4}^+) ion, no lone pairs are present on the nitrogen atom. Understanding the type of chemical bond is essential because it influences the properties and behavior of the resulting compound.