Can physics-chemistry genius explain this to me? Why in cathode ray tubes is cathode negative and anode is positive? Meanwhile in Chemistry its the other way around?
This is one of the very mysteries that will remain unsolved. I've asked both my phys tutor and phys teacher which one is more correct and neither could give a definitive answer (especially the latter, soo bad)
Historically, they had no clue about whether it was positive or negative charge that was the cause of electricity. For their convenience, you can expect why they simply assumed that the positive charge was what moved.
Conventional current is classified as the flow of "positive test charge" across a circuit. We know now that it doesn't exist, rather electron current is what actually happens. Electron current is obviously a flow of negative charge, but in reality it's just the flow of electrons.
Most of the physics that is at least taught (I can't say for sure how much of it we still apply today) is based off the original belief of conventional current. This occurs due to the fact that a ton of the physical models that we use today (heck, even the definition of CURRENT) relies on conventional current. Because it was historically assigned that charge would leave the anode and enter the cathode, in the CRT we supposedly say that it has a positive anode and negative cathode.
This is obviously not true as we know it now.
Chemistry is more interested in the behaviour of substances at the atomic level. Electrons play a crucial role as the concept of ions needs to be refurbished in the chemistry course. The chemists therefore choose to neglect the historical analysis and use the more convenient one for them.