The space that constitutes 99% of the area of an atom is the electron cloud or electron cloud model. The electron cloud refers to the region around the nucleus of an atom where electrons are most likely to be found.
In the electron cloud model, electrons are not located at specific points or orbits like planets around the sun. Instead, they exist in probability distributions called orbitals. These orbitals define the three-dimensional space where an electron is likely to be found at any given time. The shape and size of the orbitals depend on the energy level and sublevel of the electron.
The electron cloud is often depicted as a fuzzy, three-dimensional cloud-like shape around the nucleus. It represents the probability of finding an electron within a specific region. The density of the cloud represents the likelihood of finding an electron in a particular area. The regions of higher electron density are typically depicted as more concentrated parts of the cloud.
The reason why the electron cloud occupies most of the atom's volume is due to the low mass and high energy of electrons compared to the nucleus. Electrons have relatively little mass and are influenced by quantum mechanical principles, allowing them to occupy larger volumes of space. The positively charged protons in the nucleus attract the negatively charged electrons, but the electron cloud's distribution spreads out to minimize repulsion between the negatively charged electrons.
Overall, the electron cloud model provides a more accurate representation of the distribution of electrons within an atom, emphasizing their wave-like behavior and the probability of their presence in different regions.