Question

(a) Construct a Lewis structure for hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2}\), in which each atom achieves an octet of electrons. (b) Do you expect the \(\mathrm{O}-\mathrm{O}\) bond in \(\mathrm{H}_{2} \mathrm{O}_{2}\) to be longer or shorter than the \(\mathrm{O}-\mathrm{O}\) bond in \(\mathrm{O}_{2}\) ?

Short answer

The Lewis structure for hydrogen peroxide (H2O2) is: H | O - O - H with three lone pairs on each oxygen atom. The O-O bond in H2O2 is expected to be longer than the O-O bond in O2.

Step-by-step solution

Valence Electrons

In order to construct the Lewis structure of hydrogen peroxide, we first need to determine the number of valence electrons for each atom. In the periodic table, hydrogen (H) has 1 valence electron and oxygen (O) has 6 valence electrons. So, for two hydrogen atoms and two oxygen atoms, we have the following number of valence electrons: 2(H) × 1 + 2(O) × 6 = 14 valence electrons

Connect Atoms and Distribute Electrons

We know that hydrogen can only form 1 bond, so each hydrogen atom will be bonded to one of the oxygen atoms. Initially, connect the atoms with single bonds and distribute the remaining electrons: - Connecting 1 H to 1 O forms a single bond and uses 2 valence electrons, leaving 12 electrons. - Connecting the 2nd H to the other O also forms a single bond and uses another 2 electrons, leaving 10 electrons. - Now, we connect the two oxygen atoms forming a single bond, using up another 2 electrons, leaving 8 electrons. We distribute the remaining 8 electrons as lone pairs to complete the octet requirement, prioritizing oxygen atoms as hydrogen has achieved its duet rule already.

Verify Octet Rule

Let's verify if all atoms have achieved the octet rule with the current Lewis structure: - Both hydrogen atoms are connected with single bonds, so they have achieved their duet rule (2 electrons each). - Both oxygen atoms are connected to one hydrogen and the other oxygen atom with single bonds (2 electrons for each bond) and have 3 lone pairs each (2 electrons for each lone pair). So, they have achieved the octet rule with 8 electrons each.

Compare Bonds in H2O2 and O2

In the Lewis structure of H2O2, the oxygen-oxygen bond is a single bond. In O2, the oxygen-oxygen bond is a double bond. Double bonds are generally shorter and stronger than single bonds due to the added electron density between the atoms. So, we can expect the O-O bond in H2O2 (single bond) to be longer than the O-O bond in O2 (double bond). #Answer (a):# The Lewis structure of hydrogen peroxide (H2O2) can be represented as: H | O - O - H With three lone pairs on each oxygen atom. #Answer (b):# The O-O bond in H2O2 is expected to be longer than the O-O bond in O2.