How does R/S prioritization work in organic chemistry?

Question

What is the R/S priority ordering for these groups: -OH, -CH3, -Br, -CH2OH. I think it is #3, #1, #4, #2. The textbook I am reading, however, says that it is #2, #4, #1, and #3. I would ask my professor but I'm not actually in school -- I'm just studying on my own time. My reasoning is that Br has the highest atomic number (35), followed by O(8), and the of the two C atoms, CH2OH should be higher priority than CH3 because CH2OH has a link to an O(8) while CH3 only has hydrogen atoms attached to it.

Similarly, another question asks to prioritize CH2CH3, H, CH3, and CH(CH3)2. The answer key says #2, #4, #3, #1. My reasoning says that the answer is #4, #1, #3, #2.

All the other questions I appear to get correctly, using the same reasoning, so I don't understand what I'm getting wrong.

Answer 1

The correct order is -Br, -OH, -CH2OH, -CH3.

Br is the highest since it has the largest atomic number among the elements attached directly to the chiral carbon. -OH is next for the same reason. -CH2OH and -CH3 both have C as the element attached to the chiral carbon, but if we look at the elements that come next, -CH2OH has priority since it has (O,H,H) and -CH3 has only (H,H,H). Your reasoning above is completely true. Your textbook has them in reverse order and maybe it stated that they were listed from lowest priority to highest.

In the second problem, the correct order is

-CH(CH3)2, -CH2CH3, -CH3, -H from highest to lowest priority. Again I agree with you.