Question

Consider the compound whose formula is shown below. C2H40 1) Calculate the total number of valence electrons. 2) Calculate the number of bonds in the molecule. 3) Draw all possible skeleton structures representing all possible isomers. Cyclic isomers are allowed. 4) For each skeleton structure, complete its Lewis dot structure showing all electron pairs. 5) Draw resonance structures for each isomer. If a resonance structure cannot be drawn, explain why. 6) For each isomer, calculate the formal charge on each atom in each resonance structure. 7) Select the isomer that you think is most stable and explain your choice. Use the isomer selected in #7 for the following. 8) Draw dipole moment arrows on each bond. 9) What are the VSEPR geometries of each non-hydrogen atom? 10) Is the molecule polar or non-polar? How do you know?

Answer 1

I will answer 1" 3 parts of the question. Q1: Carbon, Hydrogen, Oxygen has 4, 1 and 6 valence electrons, respectively. Hence the total number of valence electrons is 2(no. of C atom)*4+4(No. of H atom)*1+1(No. of O atom)*6 = 8+4+6 = 18 Q2: To complete the Octet, Each C atom needs 4 electrons, O need two and H atom need one. If a bond forms, two electrons will be shared between 2 atoms. In effect, each atom 'gets' and an additional electron. So to stabilise, the molecule should have 4*2+2*1+1*4=14 Individual bonds. Since the Bonds are formed between the atoms of the same molecule, totally 14/2 = 7 bonds will be created. Q3: Possible Isomers H2C=C-OH H3C-C-H H₂ C CH₂