Yes, it is inaccurate to depict the nucleus as a cluster of balls. The commonly used model of the atomic nucleus as a cluster of balls is known as the "plum pudding" or "raisin pudding" model, which was proposed by J.J. Thomson in the early 20th century. According to this model, the nucleus is depicted as a positively charged sphere with embedded negatively charged electrons, similar to raisins embedded in a pudding.
However, this model was later disproven by Ernest Rutherford's gold foil experiment in 1911. Rutherford's experiment showed that the majority of the mass and positive charge of an atom is concentrated in a tiny, dense region called the nucleus, while the electrons are located outside the nucleus in electron orbitals.
The modern understanding of the atomic nucleus is based on the nuclear model developed by Rutherford, which describes the nucleus as a densely packed collection of protons and neutrons, with the electrons occupying regions of space around the nucleus. The nucleus itself is much smaller compared to the overall size of the atom.
Therefore, representing the nucleus as a cluster of balls is a simplification that does not accurately depict its structure and behavior. The actual structure of the nucleus is more complex and requires a quantum mechanical description to understand its properties.