draw a lewis structure for a resonance form of ClO2- showing the lowest possible formal charges and give the oxidation numbers of the atoms
To draw a Lewis structure for the resonance form of ClO2-, we need to follow a step-by-step process:
Step 1: Determine the total number of valence electrons.
For ClO2-, we have chlorine (Cl) with an oxidation number of -1 and oxygen (O) with an oxidation number of -2. Since there are two oxygen atoms, the overall charge of ClO2- is -1.
The valence electrons can be calculated as follows:
Number of valence electrons = Valence electrons of Cl + Valence electrons of O + Charge
= 7 (for Cl) + 6 (for O) + (-1) (charge)
= 12
Step 2: Identify the central atom.
In this case, chlorine (Cl) is the central atom as it is less electronegative than oxygen.
Step 3: Connect the atoms using single bonds.
Connect the central atom (Cl) with each oxygen atom (O) using single bonds (representing the sharing of one electron pair each). This gives us Cl-O-O.
Step 4: Place the remaining electrons.
Distribute the remaining electrons around the atoms, satisfying the octet rule (except for hydrogen, which only requires 2 electrons). In this case, first, place the remaining electrons on the outer atoms (Oxygen).
Step 5: Check if the central atom has an octet.
In this case, chlorine (Cl) does not have an octet, as it only has 6 electrons around it.
Step 6: Move electron pairs to form multiple bonds.
From step 5, we need to move electron pairs from the outer atoms to form a double bond between Cl and one Oxygen atom.
Step 7: Check if all atoms have octets.
Now, all atoms have octets: chlorine has 8 electrons (2 as a lone pair, 2 as a single bond, and 4 as a double bond), and each oxygen has 8 electrons (6 as lone pairs and 2 as shared with chlorine).
The resulting Lewis structure for the resonance form of ClO2- showing the lowest possible formal charges is:
O
//
Cl = O
In terms of oxidation numbers:
The oxidation number of chlorine (Cl) is +1.
The oxidation number of oxygen (O) in the ClO2- ion is -1.
Remember, in Lewis structures, resonance forms are indicated by double-headed arrows. The specific arrangement of electrons can vary due to resonance.