Question

Write the electron-dot structure for the covalent compound hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2}\).

Short answer

H-O-O-H with 8 lone electrons on oxygens.

Step-by-step solution

Count the Total Number of Valence Electrons

Each hydrogen atom contributes 1 valence electron, and each oxygen atom contributes 6 valence electrons. Therefore, for \(\text{H}_2\text{O}_2\), there are \(2 \times 1 + 2 \times 6 = 14\) valence electrons in total.

Determine the Skeleton Structure

Draw a skeletal structure using single bonds. Connect each hydrogen to an oxygen atom, and the oxygen atoms to each other, forming the basic framework: \(\text{H-O-O-H}\).

Distribute Remaining Electrons as Lone Pairs

After the bonds are drawn, the structure uses 6 electrons (3 bonds with 2 electrons each). Distribute the leftover 8 electrons as lone pairs on the oxygen atoms to complete the octet rule for them.

Verify the Octet Rule and Total Electrons

Ensure each oxygen atom has a complete octet. Each oxygen will have 2 bonded electrons and 4 lone electrons (2 pairs), totaling 8 electrons each. Also, confirm that the total of 14 valance electrons are accounted for in the structure.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom. They play a crucial role in chemical bonding and reactivity. When determining how atoms will bond with each other, focusing on the valence electrons helps us predict the structure and properties of molecules.

In the case of hydrogen peroxide \(\mathrm{H}_2\mathrm{O}_2\), each hydrogen atom has 1 valence electron, and each oxygen atom has 6. Knowing this allows us to calculate the total number of electrons available for bonding. Here, the calculation is simple:

• Hydrogen: \(2 \times 1 = 2\) electrons
• Oxygen: \(2 \times 6 = 12\) electrons

This gives a total of 14 valence electrons, which are used to form bonds and lone pairs in the molecule.

Octet Rule

The octet rule is a key principle in chemistry. It states that atoms tend to form bonds until they are surrounded by eight electrons in their valence shell. Achieving this stable arrangement makes the molecule more stable.

In the case of hydrogen peroxide, the goal is to have each oxygen atom satisfied the octet rule with 8 electrons. Here's how it works:

• Each oxygen forms two bonds (one with hydrogen, one with another oxygen), using 2 electrons from each bond.
• The remaining electrons are arranged as lone pairs to fill each oxygen atom's valence shell.

Hydrogen, however, is an exception to the octet rule as it is stable with just 2 electrons, corresponding to the \(1s^2\) shell. It's important to verify that each atom satisfies these rules in a stable molecule.

Covalent Compounds

Covalent compounds occur when atoms share electrons. They do this to achieve a full valence shell, often aiming for a noble gas configuration.

In hydrogen peroxide \(\mathrm{H}_2\mathrm{O}_2\), covalent bonds are formed:

• Between hydrogen and oxygen (single bond)
• Between the two oxygen atoms (single bond)

This sharing allows each atom to effectively "see" 8 electrons, conforming to the octet rule. These shared pairs create strong bonds making covalent compounds generally stable. Covalent bonding explains much about the reactivity and properties of molecules.

Hydrogen Peroxide

Hydrogen peroxide is a common and interesting covalent compound with uses ranging from cleaning to chemical reactions. In its electron-dot structure, the placement of electrons is vital for understanding its reactivity.

Following the electron-dot structure steps:

• Start by placing single bonds between the atoms: \(\mathrm{H-O-O-H}\).
• Then distribute the remaining valence electrons to complete oxygen’s octet.

This ensures that the hydrogen atoms have 2 electrons and each oxygen atom has 8 electrons. It’s a straightforward yet insightful way to visualize the molecule's bonding and structure, helping us grasp how it interacts chemically.