Iron is found both in the blood and in the iron nail. When is iron a chemical element?

In the blood, iron is a chemical element, the center of complex hemoglobin molecules.

In the composition of an iron nail, we are talking about iron as a simple substance with physical properties. The iron of a nail (a simple substance) is made up of atoms of the chemical element ferum (iron).

One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.