In the depths of our solar system – a realm where chemistry and speculation collide – scientists have reported the possible existence of a molecule known as aquodiium, an elusive cousin of the ammonium ion. If true, it could explain the oddities in the magnetic fields of Neptune and Uranus.
This is a major problem because stable aquodiium, which consists of four hydrogen atoms and one oxygen atom (H4O2+), has never been observed before due to the high energy barrier involved in adding a second proton to the molecule of hydronium (H3O+). this is how aquodiium must be formed. However, hydronium is a little easier to make. It is created by the fundamental process of adding a proton to water. The jump from hydronium to aquodiium is the hardest part.
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However, using advanced computer models, researchers have discovered a potential habitat for aquodiium: the extreme pressure found in the cores of the ice giants Uranus and Neptune. And importantly, its presence in this intense, icy environment could help explain the planets’ unusual magnetic fields; strangely, they are both highly tilted with respect to their axis of rotation and significantly offset from the centers of the planets.
Could aquodiium be to blame?
Peculiar chemistry for peculiar worlds
Because they have similar size and mass, the nuclei of Neptune and Uranus are virtually identical. Both have rocky cores like Jupiter and Saturn, but unlike their larger neighbors, their internal pressure is not sufficient to convert molecular hydrogen into an electrically conductive liquid metal. Instead, a large mantle of icy water and ammonia forms about 12,000 miles below the surface of these worlds.
Here’s where things get interesting: the study authors suggest that the planets’ unusual magnetic fields could be generated by ions acting as charge carriers. Ions are atoms or molecules with a net electric charge resulting from the loss or gain of one or more electrons. These ions that relate to the magnetic fields of Uranus and Neptune do not have to exist only as protons in their own right, but can also include hydronium, ammonium and aquodiium.
In chemistry, a molecule generally exists in its lowest energy form, known as the ground state. This is because nature tends to follow the path of least resistance, and the ground state minimizes factors such as bond tension, which means that atoms within the molecule are bonded together at less than ideal angles, and electrostatic repulsion, where charged atoms or groups within the molecule are connected. molecules repel each other. The challenge in forming aquodiium (H4O2+) lies in the increased electrostatic repulsion and tension that occurs when adding a second proton to the hydronium ion – it’s like trying to bring two positively charged magnets together.
When a proton is added to water to form hydronium, these two factors can be more easily overcome; the resulting molecule has a positive charge located on only one of the oxygen atoms, with the hydrogen atoms arranged in a stable geometry around the oxygen atom at the center. To go from this situation to aquodiium, you would have to add a second proton to the structure – but that would increase the amount of positive charge in the molecule, leading to significant electrostatic repulsion between both positively charged protons and disrupting the existing structure of the hydronium. molecular structure, which creates tension.
Under normal conditions, these factors ensure that stable aquodiium cannot form. The only way this would be possible would be if there was enough energy in the reaction power the molecule has to come together anyway, amid all the tension, repulsion and other complications that are not even discussed. We don’t have that kind of energy on Earth. However, under the extreme conditions in Uranus and Neptune, there may indeed be sufficient energy.
The scientists reported that aquodiium appeared as a plausible outcome in their simulations, especially because the very high pressures in these worlds promote the binding of oxygen and hydrogen ions so that aquodiium can be stabilized. And if stable aquodiium lurks on these planets, we may finally be on the way to figuring out where they get their strange magnetic fields from.
The research was published in May in the news Physical examination B.