* Nuclear Structure: Helium has a nucleus containing two protons and two neutrons. Hydrogen has a nucleus containing only one proton. You can't simply "split" the helium nucleus to get two hydrogen nuclei because the number of protons defines the element.

* Energy Requirements: Breaking apart the nucleus of an atom requires a tremendous amount of energy, typically achieved in nuclear reactions. Splitting helium into hydrogen would require more energy than you would get back from the process, making it energetically unfavorable.

What can happen to Helium:

* Nuclear Fusion: Under extremely high temperatures and pressures, like those found in stars, helium can fuse with another helium atom to form beryllium. This process is a key part of how stars generate energy.

* Radioactive Decay: Some isotopes of helium (like helium-3) are radioactive and can undergo decay, but this doesn't result in splitting into hydrogen. It involves the emission of particles like protons or neutrons.

In summary: While helium and hydrogen are both light elements, their nuclear structures are fundamentally different, preventing a simple splitting of helium into hydrogen.