So as someone who’s done A level chemistry, please know that at this early stage, spending this long on early topics to understand the content and make notes in COMPLETELY normal. I remember breaking down and crying when I learnt how electron shells are really structured and it took me at least 3 hours just to understand the two pages of the textbook it took up. It will get much much easier to understand content quicker as you go along and get to grips with the new style of content. One thing I would recommend might be to have the spec on hand when making notes, as exam boards won’t ask questions other than content mentioned on the spec (I didn’t know this until I made revision notes but I WISH someone had told me this earlier). I gave up reading ahead after a couple of weeks, I found it much more time efficient to make notes fresh on a topic during lesson, and spend time afterwards collating class notes, textbook pages etc into my final notes, without knowing I’d have to prep for the next lesson. Obviously, do whatever method works for you, that’s just what worked for me. Hope this helps x