Final answer:
The kinetic energy of an electron decreases as it moves away from the nucleus because the electrostatic attraction, which contributes to the electron's kinetic energy, diminishes with distance. At higher energy levels, electrons have less kinetic energy but more potential energy, reflecting the balance between these energy forms as per the conservation of energy principles.
Step-by-step explanation:
The question of why the kinetic energy decreases as electrons move away from the nucleus can be understood by discussing the principles of electrostatic attraction in atomic physics. Electrons are negatively charged particles that are attracted to the positively charged nucleus due to electrostatic forces. The closer an electron is to the nucleus, the stronger this force of attraction, and the more energy it has in the form of kinetic energy. However, as the electron moves away from the nucleus, this attraction decreases, leading to a reduction in the electron's kinetic energy.
When an electron moves to a higher energy level (higher principal quantum number, n), it is found further from the nucleus. According to the electrostatic principles, as the electron's distance from the nucleus increases, its potential energy increases while its kinetic energy decreases. The higher energy level corresponds to a state where the electron is held less tightly and is manifested in a higher potential energy, thus fulfilling the need for conservation of energy.