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.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons