Yeah sodium is very reactive so in laboratory sodium is kept in special manner so that it doesn’t react and change into another compound. Natural sodium is a soft metal, it should not be consumed or touched. It caches fire very easily so should be work carefully. So yes natural sodium is bad for us. But inside our body we need sodium, so we consume sodium chloride(NaCl) (common salt). It breaks inside our body and give the necessary sodium for our body. We can’t live without sodium and we can’t consume direct sodium.
Do you mean sodium naturally occurring in foods? In this case no – it’s not bad for you. The problem is too much of it is. We should eat only about 1.5 g of sodium per day, but many of us eat ca. 10 g per day, increasing our risk of heart disease and stroke.