Why does it take so much heat and pressure to create helium and other elements?

To break down the nucleus of an atom

Explanation:

Remember to change from one element to another, is necessary to add protons, neutrons and electrons,in most of the cases.

The take an electron from an atom you need certain energy, but they are in the outside part of the atom so is not as much energy as the one is necessary to take one neutron or proton from the inside part of an atom.

In this way, is a must to have a combination of pressure and heat to destabilize an atom and take some of this subatomic particles.

i believe that it is a exoplanet

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.