Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to learn about the chemistry of the hydrogen atom [title] Hydrogen atom is the simplest atom of all the elements in the periodic table. [step] It is composed of a proton which is confined to the nucleus and an electron which circulates around the nucleus in circular motion. It is the third element in abundance on earth after oxygen and silicon.

Ending1: [substeps] The space ion is the ship in the multi tiny orbit system known as the half wall. The gas ion is an object within the multiatom. Ending2: Its simple structure attracted the attention of physicist as to predict the structure of the atom not known for sure at that time. The bohr theory of the hydrogen atom was the first successful theory that predicted the structure and energetics of the hydrogen atom. Ending3: Solubility is determined by subatomic forces. Note that this is a matter of fusion. Ending4: It is also located on the equilateral triangle pattern. The other atom is lower and less gas than hydrogen atom, but still light enough to use well to create a molecule.

Answer format: ending1/ending2/ending3/ending4