When pronouncing س and ص, am I correct to say that your tongue should slightly touch the alveolar ridge, but the tip of your tongue leaves an opening for air to pass through, which creates the sound. Or must the tongue not touch the roof of your mouth at all?
Wa alikom asslam,
The positioning of the س and ص is not the same for these two sounds, for the ص the tongue is raised higher, but not touching the palate or the alveolar ridge. This means that س also does not require you to make contact with the tongue, the tip of the tongue is more behind the front teeth, where the air comes out.
Make sure to check this comparison video https://www.youtube.com/watch?v=9WvCOlcLSHQ
Allah knows best.