The size of an atom's nucleus is significantly smaller compared to its electron cloud. The nucleus is located at the center of an atom and contains positively charged protons and usually uncharged neutrons.
The size of an atomic nucleus can vary depending on the element. Typically, the diameter of an atomic nucleus ranges from about 1 to 10 femtometers (1 femtometer = 1 x 10^(-15) meters). For example, the diameter of a hydrogen nucleus (a single proton) is approximately 1.75 femtometers, while the diameter of a uranium nucleus (with many protons and neutrons) can be around 14 femtometers.
In contrast, the electron cloud surrounding the nucleus is much larger. The electron cloud represents the region in which electrons are likely to be found. According to quantum mechanics, electrons do not follow precise paths like planets around the Sun but are described by wave functions, which determine the probability of finding an electron at different locations.
The size of the electron cloud is typically estimated using various parameters, such as the electron density or the average distance from the nucleus where the electron probability density drops to a certain threshold. The electron cloud extends far beyond the nucleus and occupies a relatively large volume of space compared to the nucleus.
It's important to note that the electron cloud does not have a sharp boundary but rather gradually diminishes in electron probability as you move further away from the nucleus. The exact shape and size of the electron cloud depend on the specific electron distribution and atomic orbital configurations within the atom.
In summary, the size of an atom's nucleus is significantly smaller compared to its electron cloud. The nucleus is a tiny, dense region at the center, while the electron cloud occupies a much larger volume surrounding the nucleus.