Which of the following best describes the Lewis dot structure for the tert-butyl cation, (CH3)3C+?

• A. The central carbon atom is bonded to three methyl groups and has one lone pair, with eight electrons around it.
• B. The central carbon atom is bonded to three methyl groups and has two lone pairs, with ten electrons around it.
• C. The central carbon atom is bonded to four methyl groups and has no lone pairs, with eight electrons around it.
• D. The central carbon atom is bonded to three methyl groups and has no lone pairs, with only six electrons around it.

Answer: (D)

Verified step by step guidance

1. Identify the structure of the tert-butyl cation, (CH3)3C+. It consists of a central carbon atom bonded to three methyl groups (CH3) and carrying a positive charge.
2. Recall that carbon typically forms four bonds to satisfy the octet rule, having eight electrons around it. However, in a carbocation like tert-butyl cation, the central carbon has only three bonds and a positive charge, meaning it has only six valence electrons and no lone pairs.
3. Understand that the positive charge on the central carbon indicates it is electron-deficient, so it does not have any lone pairs. Lone pairs would add electrons, which contradicts the positive charge.
4. Draw the Lewis structure by placing the central carbon atom bonded to three methyl groups, with no lone pairs on the central carbon, and indicate the positive charge on the central carbon.
5. Verify the electron count around the central carbon: three single bonds contribute 2 electrons each (total 6 electrons), confirming the electron deficiency consistent with the carbocation.