I need help understanding how chemical reactions work.

I started learning chemistry recently but I have a really hard time understanding reactivity.

When i look through my notes i see different reactions , but the problem is I dont understand how to know what elements react with what and what is produced. I covered electronegativity , ionisation energy and electron affinity. How do I know what chemicals react with , how to identify and know that this chemical react with this but not this, this reaction produces these specific products? . The only thing I know is hydroxides break in extreme heat to form oxides and hydrogen gas...or was it water vapour ( H2O) , like I literally don't know how to identify what forms. I'm sorry if this post is stupid but I am genuinely so confused. Not to mention I'm stl stuck at inorganic nomenclature