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

let that person have a turn to speak : )

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.