The Lewis structure for the chlorate ion, ClO3, should show single bond(s), double bond(s), and lone pair(s). (Chlorine is the central atom) A) 1,2,7 B) 3 0-9 7-5-2 – 25 2 877 +0 = )be (1,2, 8 6-2-4 O 6-2-4
The Correct Answer and Explanation is:
The correct answer is 1, 2, 8.
The Lewis structure for the chlorate ion, ClO₃⁻, is determined by finding the arrangement that minimizes formal charges, which often requires using double bonds and expanding the octet of the central atom.
First, we calculate the total number of valence electrons. Chlorine (Group 17) contributes 7 valence electrons. Each of the three oxygen atoms (Group 16) contributes 6 electrons, for a total of 18. The ion has a negative one charge, so we add one more electron. This gives us a total of 7 + (3 * 6) + 1 = 26 valence electrons to distribute.
With chlorine as the central atom, we initially draw single bonds to each of the three oxygen atoms. This uses 6 electrons. Distributing the remaining 20 electrons as lone pairs, we first satisfy the octets of the terminal oxygen atoms (3 lone pairs each, using 18 electrons), and the final 2 electrons go on the central chlorine atom.
At this stage, every atom has a full octet. However, calculating the formal charges reveals an unstable arrangement. Each singly bonded oxygen has a formal charge of -1, and the chlorine atom has a formal charge of +2. The best Lewis structure is one that minimizes these formal charges.
To reduce the charges, we can move lone pairs from two of the oxygen atoms to form two double bonds with the chlorine atom. Chlorine, being in the third period, can accommodate an expanded octet. In this new arrangement, we have two double bonds and one single bond. The formal charge on each double bonded oxygen becomes 0, the formal charge on the singly bonded oxygen is -1, and the formal charge on the central chlorine atom is now 0. This structure is far more stable.
Therefore, the most representative Lewis structure for the chlorate ion shows:
- 1 single bond (Cl-O)
- 2 double bonds (Cl=O)
- 8 total lone pairs (one on chlorine, two on each double bonded oxygen, and three on the singly bonded oxygen).
