Hi there! quick question: why are some elements more reactive to other elements?

valence electrons.

sodium only has one valence electron on its outer shell so it is very easy for it get rid of it and a lot of other elements wanna mess with it. but something like argon has full valence shell so it does not do anything with its electrons since its alreadt full. the atoms want to get a full shell, so sodium wants to lose it asap

"hydrogen bonding is the attraction of h atoms in the water molecule (slight + charge) to o atoms in a neighboring water molecule (slight - charge); it is a weak interatomic force. but it is still strong enough to the water molecules "stick" together."