HO2- Lewis structure

HO₂^– has one hydrogen atom and two oxygen atoms.

In the HO₂^– Lewis structure, there are two single bonds around the oxygen atom, with hydrogen and oxygen atoms attached to it, and on the right oxygen atom, there are three lone pairs.

Also, there is a negative (-1) charge on the right oxygen atom.

Alternative method: Lewis structure of HO₂^–

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, hydrogen lies in group 1, and oxygen lies in group 16.

Hence, hydrogen has one valence electron and oxygen has six valence electrons.

Since HO₂^– has one hydrogen atom and two oxygen atoms, so…

Valence electrons of one hydrogen atom = 1 × 1 = 1
Valence electrons of two oxygen atoms = 6 × 2 = 12

Now the HO₂^– has a negative (-1) charge, so we have to add one more electron.

So the total valence electrons = 1 + 12 + 1 = 14

Learn how to find: Hydrogen valence electrons and Oxygen valence electrons

• Second, find the total electron pairs

We have a total of 14 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 14 ÷ 2 = 7

• Third, determine the central atom

Here hydrogen can not be the central atom. Because the central atom is bonded with at least two other atoms, and hydrogen has only one electron in its last shell, so it can not make more than one bond.

Now, there are only two atoms and both atoms are oxygen, so we can assume any one as the central atom.

Let’s assume that the central atom is center oxygen.

Therefore, place one oxygen in the center and hydrogen and other oxygen on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 7 electron pairs. And two bonds are already marked. So we have to only mark the remaining five electron pairs as lone pairs on the sketch.

Also remember that oxygen is a period 2 element, so it can not keep more than 8 electrons in its last shell. And hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are hydrogen and right oxygen. But no need to mark on hydrogen, because each hydrogen has already two electrons.

So for right oxygen, there are three lone pairs, and for center oxygen, there are two lone pairs.

Mark the lone pairs on the sketch as follows:

Formal charge

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0

For center oxygen atom, formal charge = 6 – 4 – ½ (4) = 0

For right oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

Here, the right oxygen atom has a charge, so mark it on the sketch as follows:

Final structure

The final structure of HO₂^– features a central oxygen atom linked to a hydrogen atom and a second oxygen atom through single covalent bonds. In this arrangement, the central oxygen atom satisfies the octet rule by forming two bonds and retaining two lone pairs, while the terminal oxygen atom fulfills its octet by forming one bond and retaining three lone pairs. Within this layout, the hydrogen atom achieves a stable duet. This configuration represents the most stable state for the ion because the negative formal charge is localized on the more electronegative terminal oxygen atom. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of HO₂^–.

To properly represent this as a polyatomic ion, the entire Lewis structure is enclosed within square brackets. The overall charge of 1- is then written as a superscript outside the brackets at the top right, indicating that the structure possesses one additional electron beyond the valence count of the neutral atoms.

Next: NH₂OH Lewis structure

External links

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