The air we breathe is not considered by chemists to be an element. why not

Explanation:

An element is a substance that cannot be broken down by an ordinary physical process. An element is made up of atoms having the same atomic number. There is a periodic table of elements that has all the elements arranged according to there atomic number.

Air is not an element because it actually contains atoms of more than one element (including oxygen, nitrogen and noble gases). Air also contains compounds such as CO₂. These substances that air contains are physically combined, hence air is a mixture.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.