MCAT Chemistry Question — Oxygen
- Jan 31, 2017
- MCAT Question of the Day
A. -1, 0, -3
B. +2, 0, +2
C. +1, 0, -1
D. +5, +4, +7
Click for Explanation
Stated more loosely, the formal charge is the number of electrons an atom “wants” to have minus the dots minus the sticks. So, for example, for the oxygen on the left, we know that oxygen “wants” to have six electrons. It’s got two dots and three sticks. So 6 – 2 – 3 = +1
A. -1, 0, -3, incorrect, Uses formal charge = -valence e– + ( e– in lone pairs + 1/2 bonded e–).
B. 2, 0, 2, incorrect, Uses formal charge = -valence e– + ( e– in lone pairs + bonded e–).
C. 1, 0, -1, correct.
D. 5, 4, 7, incorrect, Uses formal charge = e– in lone pairs + 1/2 bonded e–.
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