1. The problem statement, all variables and given/known data How many sp3-hybridized carbon atoms does tamoxifen possess? This is tamoxifen: http://en.wikipedia.org/wiki/File:Tamoxifen_Structural_Formulae.png 2. The attempt at a solution Are all carbons sp3-hybridized? Does the hybridization of carbon vary, depending on the bonds (ie. single, double, triple), and what it bonds to? This is a multiple choice question, and the options are 2, 4, 6, 7, and 11... so it wouldn't work if I just counted the number of carbons (there would be 26). If this is the case, I don't understand how to determine the number of sp3-hybridized carbons. Wouldn't carbon ALWAYS be sp3-hybridized, since there are three 2p orbitals, and one 2s orbital that holds carbon's valence electrons?