The energy of an electron in an atom is determined by its position and the forces acting on it. In the context of atomic structure, electrons occupy specific energy levels or orbitals around the nucleus. These energy levels are quantized, meaning they can only have certain discrete values.
In the most commonly used model, the electron energy levels in an atom are described by the Bohr model or the quantum mechanical model. According to these models, electrons closer to the nucleus have lower energy levels, while electrons farther from the nucleus have higher energy levels.
The energy of an electron in an atom is influenced by the attractive force between the negatively charged electrons and the positively charged nucleus. This force is known as the electrostatic force or the Coulombic force. The closer an electron is to the nucleus, the stronger the electrostatic attraction between them.
As an electron moves away from the nucleus to a higher energy level or orbital, it is further from the positively charged nucleus. The electrostatic force of attraction decreases, resulting in higher energy for the electron. The energy levels in an atom are often represented as a series of shells or orbitals, with the innermost shell having the lowest energy and the outermost shell having the highest energy.
It's important to note that this explanation is a simplified model of electron behavior in atoms. In reality, electron behavior is better described by quantum mechanics, which involves wave functions and probability distributions. Nonetheless, the concept that electrons closer to the nucleus have lower energy than those farther away still holds true in quantum mechanics.