The reason electrons do not collide with each other when they are in the same orbit around the nucleus of an atom is primarily due to quantum mechanics and the principles governing electron behavior.
In the quantum mechanical model of the atom, electrons are described by wave functions and exist in specific energy levels or orbitals around the nucleus. These energy levels are quantized, meaning they have discrete and distinct values.
The Pauli exclusion principle, formulated by Wolfgang Pauli, is a fundamental principle in quantum mechanics that states that no two electrons in an atom can have the same set of quantum numbers. This principle ensures that each electron within an atom occupies a unique quantum state.
The combination of the Pauli exclusion principle and the quantization of energy levels results in a distribution of electrons in different orbitals. Each orbital can hold a specific number of electrons, and within an orbital, the electrons have different spin states.
Electrons in the same orbital have opposite spin states, meaning they have opposite spins (+1/2 and -1/2). This spin pairing helps to stabilize the electron configuration and prevents them from colliding with each other.
Additionally, electrons are subject to the electromagnetic force, which governs the interactions between charged particles. Electrons repel each other due to their negative charges, and this repulsive force prevents them from getting too close to each other. The repulsion between electrons counteracts the gravitational attraction of the nucleus, helping to maintain their stable orbitals.
In summary, the combination of the Pauli exclusion principle, the quantization of energy levels, the pairing of electrons with opposite spins, and the electromagnetic repulsion between electrons ensures that they do not collide with each other within the same orbit around the nucleus of an atom.