When an electron is emitted from the nucleus of an atom, it typically occurs through a process called radioactive decay. There are several types of radioactive decay, including alpha decay, beta decay, and electron capture. The specific type of decay depends on the characteristics of the nucleus and the specific atom involved.
In the case of beta decay, which is the most common process for electron emission, an unstable atomic nucleus undergoes a transformation to achieve a more stable state. During beta decay, a neutron inside the nucleus is converted into a proton, and an electron (called a beta particle) is emitted. The electron is then released from the nucleus with a certain amount of kinetic energy.
The emission of the electron changes the composition of the atom. The number of protons increases by one since a neutron is converted into a proton, while the number of neutrons decreases by one. As a result, the identity of the atom changes, and it becomes an atom with one higher atomic number.
It's important to note that the electron emitted during beta decay originates from the nucleus, not from the electron cloud surrounding the nucleus. Electrons in the electron cloud occupy distinct energy levels or orbitals, and they are not directly involved in the emission process from the nucleus.