How is the compound sodium chloride different from the elements of which it is composed?

Sodium chloride as we know is table salt which we usually used in our food as condiments. However, the individual components that makes them are highly dangerous. Sodium is a very reactive metal that upon contact with water or air, they become explosive. Chlorine, a gas, is very poisonous and was one of the most lethal weapons used during ww2. But when they are formed to become sodium chloride, the properties have completely changed and hence are different from sodium and chlorine properties.

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts