Draw the Lewis structure for iodoethane
. Be certain you include any lone pairs.
The Correct Answer and Explanation is:
To draw the Lewis structure of iodoethane (C₂H₅I), follow these steps:
Step 1: Count the Total Number of Valence Electrons
Each element in the molecule contributes electrons based on its group in the periodic table:
- Carbon (C) is in Group 14, so each carbon atom has 4 valence electrons. Since there are two carbon atoms, the total from carbon is 2×4=82 \times 4 = 82×4=8 electrons.
- Hydrogen (H) is in Group 1, so each hydrogen atom has 1 valence electron. Since there are five hydrogen atoms, the total from hydrogen is 5×1=55 \times 1 = 55×1=5 electrons.
- Iodine (I) is in Group 17, so iodine has 7 valence electrons.
So, the total number of valence electrons is:8 (from C)+5 (from H)+7 (from I)=20 electrons.8 \, (\text{from C}) + 5 \, (\text{from H}) + 7 \, (\text{from I}) = 20 \, \text{electrons}.8(from C)+5(from H)+7(from I)=20electrons.
Step 2: Determine the Skeleton Structure
Iodoethane consists of an ethyl group (C₂H₅) attached to an iodine (I) atom. The skeleton structure is:
- One carbon (C) atom bonded to three hydrogens (H) and the second carbon (C) atom.
- The second carbon is bonded to two hydrogens (H) and an iodine (I) atom.
Step 3: Distribute Electrons
Now, we place single bonds between the atoms:
- Each C-H bond uses 2 electrons. With five C-H bonds, that consumes 5×2=105 \times 2 = 105×2=10 electrons.
- The C-C bond between the two carbons uses 2 electrons.
So far, we’ve used 10+2=1210 + 2 = 1210+2=12 electrons. That leaves 20−12=820 – 12 = 820−12=8 electrons to be placed.
Step 4: Assign Lone Pairs
The remaining 8 electrons should be placed as lone pairs:
- Each carbon atom already has 8 electrons in its bonds, so no lone pairs are placed on the carbons.
- The iodine atom (I) has 7 valence electrons. After forming a single bond with carbon, it will have 6 remaining electrons, which are placed as 3 lone pairs around iodine.
Step 5: Check for Octet Rule
All atoms should satisfy the octet rule (except hydrogen, which needs only 2 electrons):
- The two carbon atoms have 8 electrons each, fulfilling the octet rule.
- Each hydrogen atom has 2 electrons from its bond with carbon.
- The iodine atom has 8 electrons, including 3 lone pairs and the 1 electron from the bond with carbon.
Final Structure:
- C₆H₁₂I with bonds between the two carbon atoms and iodine, with 3 lone pairs on the iodine atom.
Thus, the Lewis structure of iodoethane should look like this:
mathematicaCopyEdit H H
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H-C-C-I
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H H
The iodine atom has three lone pairs, and all atoms follow the octet rule, except for hydrogen which follows the duet rule.
