Determine the formal charge of each element in H₃O⁺

To determine the formal charge of each element in the hydronium ion (H₃O⁺), we first need to identify the structure of the molecule.

In H₃O⁺, we have one oxygen atom and three hydrogen atoms. The oxygen atom has six valence electrons in its outer shell, while each hydrogen atom has one valence electron. When we combine these atoms, the oxygen atom forms single bonds with the three hydrogen atoms.

Now, let’s calculate the formal charge for each atom using the formula:

Formal Charge = Valence Electrons – (Non-bonding Electrons + 0.5 * Bonding Electrons)

1. Oxygen Atom:

Oxygen has:

• 6 valence electrons.
• 2 lone pair electrons (non-bonding).
• 6 bonding electrons (3 single bonds with hydrogen, so 3 bonds x 2 electrons per bond = 6).

Plugging into the formula:

Formal Charge of Oxygen = 6 – (2 + 0.5 * 6)

Formal Charge of Oxygen = 6 – (2 + 3) = 6 – 5 = 1

2. Hydrogen Atoms:

Each hydrogen atom has:

• 1 valence electron.
• 0 non-bonding electrons.
• 2 bonding electrons (1 bond with oxygen).

For each hydrogen atom:

Formal Charge of Hydrogen = 1 – (0 + 0.5 * 2)

Formal Charge of Hydrogen = 1 – 1 = 0

Since there are three hydrogen atoms, the formal charge for each hydrogen atom is 0.

In conclusion, in H₃O⁺, the formal charge of the oxygen atom is +1, and the formal charge of each hydrogen atom is 0. Thus, the overall charge of the molecule is +1, which corresponds to what we expect for the hydronium ion.