The statement that the atom consists of electrons and empty space is a simplified way of describing the structure of an atom based on classical physics. In reality, the behavior of particles at the atomic scale is described by quantum mechanics, which is more complex and nuanced.
According to quantum mechanics, electrons do not behave like tiny particles moving in well-defined orbits around the nucleus, as depicted in classical models. Instead, electrons are described by wave functions that represent the probability distribution of finding an electron in a particular region of space. These wave functions have certain energy levels or "orbitals" associated with them.
The idea that atoms are mostly empty space arises from the fact that the size of the electron's wave function or orbital is much larger than the size of the nucleus. This means that there are regions of space within the atom where the probability of finding an electron is very low, often referred to as "electron clouds" or "electron orbitals." These regions of low electron density create the perception of empty space within the atom.
However, it is important to note that even though the electron's wave function may extend over a large region of space, it does not simply float away. The wave function describes the probability distribution of finding an electron, and the electron is still bound to the atom by the attractive force between the negatively charged electrons and the positively charged nucleus. This force, known as the electromagnetic force, keeps the electron within its allowed energy levels or orbitals.
In summary, while the notion of the atom consisting of electrons and empty space is a simplification, it reflects the probabilistic nature of electron behavior in quantum mechanics. The electron's wave function extends over a large region, but it remains bound to the atom due to the electromagnetic forces acting on it.