Element or compound that enters into a chemical reaction undergoes what process

Depends on the conditions of reaction.

Explanation:

Any element or compound that enters into a chemical reaction can undergoes any process depending of the conditions of reaction, for example, temperature, pressure, medium, among others.

A chemical reaction is a process in which any substance, element or process undergoes chemical and physical changes.

In chemical reaction we have reactants, that is the innitial or starting elements or compounds; products which are the result of the reaction between the reactants and we might see physical changes.

For example, if we do a reaction betwenn Iron and oxygen:

4Fe + 3O2 > 2Fe2O3

Iron and oxygen reacts and creates a new product. This is the iron oxyde, which is a physical change too, and you can see that for a color change.

Depending on conditions, we can have several types of chemical reaction, such as synthesis, decomposition, single displacement, double displacement, equilibrium reactions, acid - base reactions among others.

electron microscopy and scanning tunneling microscopes gives us a greater understanding of atoms by being able to see the atom itself, and lets us see some atomic reactions.

explanation:

a polar bond is formed when electrons are shared unevenly between atoms