Physicists long believed that atomic nuclei were round, but recent discoveries have revealed a more complex picture. The nucleus, made up of protons and neutrons, is surprisingly not spherical, but rather takes on various shapes, including the classic American football shape.
The idea of a spherical nucleus was first proposed in 1911, but it wasn’t until the 1940s that scientists developed the nuclear shell model. This model predicted that protons and neutrons would occupy distinct energy levels, similar to electron shells in atomic physics.
However, as physicists delved deeper into the behavior of nuclei, they discovered that most nuclear properties were better explained by collective behavior rather than individual particles. In other words, the nucleus as a whole acts like a single object that can rotate or vibrate.
Spectroscopic methods have shown that rotation is not possible in symmetrical systems like atoms, unless the nucleus is deformed. Researchers found that about 90% of nuclei take on a prolate deformed shape, while only a small percentage are spherical or have multiple shapes.
But why do some nuclei adopt these shapes? Scientists believe it has to do with quantum mechanics and the way particles interact. The Schrödinger equation, a fundamental principle in quantum mechanics, predicts that an atomic nucleus would be shaped like a circle, but due to wave function solutions, particles are more likely to point in one direction.
The discovery of non-spherical nuclei is “overturning a legacy” and raises many open questions. While the exact reason for these shapes remains unknown, researchers continue to explore this fascinating topic and uncover new insights into the behavior of atomic centers.
Source: https://www.livescience.com/physics-mathematics/why-isnt-an-atoms-nucleus-round