Question

why do iron filling get get burn whereas iron doesn't?

Answer 1

because the iron has strong force of attraction between the atoms hence it doesn't burn on heating but where as if we burn iron fillings then the flame encloses the iron fillings and force of attraction between them cannot balance the situation and hence it burns vigorously

Answer 2

Explanation:

Iron has a strong molecular force of attraction. Hence when heated it doesn't reach to its ignition temperature and doesn't burn. But iron fillings when sprinkled in flames attain the ignition temperature ( as iron fillings are comparatively smaller particles) and gain larger surface area for the reaction.