12.1 - Properties of the alkanes

Question 1

general formula of alkanes

Answer 1

CnH2n+2

Question 2

bonding in alkanes

Answer 2

atoms joined together by single covalent bonds

sigma bonds - direct overlapping of two orbitals, one from each bonding atom

Question 3

shape of alkanes

Answer 3

tetrahedral - each C atom surrounded by 4 electron pairs in 4 sigma bonds
109.5 degrees

Question 4

what is the trend in boiling point as the chain length of alkanes increase?

Answer 4

the boiling point increases because molecules have a larger surface area, so there is more surface contact, resulting in stronger London forces.

Question 5

what affect does branching have on boiling point of alkanes?

Answer 5

branching decreases boiling point,
because there are fewer surface points of contact between molecules,
so there are weaker London forces.