Question

In the Bohr model, how does the electron move to a higher-energy orbit or to a lower-energy orbit?

Short answer

An electron moves to a higher-energy orbit by absorbing energy, often provided in the form of a photon. The energy absorbed is equal to the difference between the two energy levels. To move to a lower-energy orbit, an electron releases energy, equal to the difference between the two orbits, in the form of a photon.

Step-by-step solution

Understand the Bohr Model

In the Bohr model, an atom is composed of protons and neutrons in the nucleus, with electrons revolving in fixed orbits around the nucleus. These orbits are associated with specific energy levels. In this model, the energy of an electron is quantized, meaning it can only exist in these specific states and nowhere in between.

Transition to a higher-energy orbit

According to Quantum Theory, for an electron to move from a lower-energy orbit (state) to a higher-energy orbit, it must absorb a specific amount of energy. This energy is often provided in the form of a photon. The absorbed energy is equal to the difference in energy levels between the two orbits. The electron absorbs this energy, making an 'upward' transition to the higher-energy orbit.

Transition to a lower-energy orbit

Conversely, for an electron to move from a higher-energy orbit to a lower-energy orbit, it must release a specific amount of energy. This release of energy also takes the form of a photon. The energy of the photon (energy released) is equal to the difference in energy levels between the two orbits. The electron 'drops down' to the lower-energy orbit, and the energy difference is emitted in the form of a photon.

Key concepts

Electron Transitions

Electron transitions are key movements within atoms as dictated by the Bohr model. These transitions occur between different energy levels or orbits within an atom.
To understand this better, think of an electron as being able to "jump" from one orbit to another. These orbits are not arbitrary; they are fixed paths predefined by very specific energy levels. This means an electron can't just exist anywhere around the nucleus but must be in one of these designated paths.
When an electron moves 'up' to a higher-energy orbit, it absorbs energy in the form of a photon. This energy amount is precise and matches the difference in energy between the two orbits. Similarly, when an electron transitions 'down' to a lower-energy orbit, it releases energy, again in the form of a photon, equivalent to the difference in energy levels. Understanding these transitions is crucial in fields such as spectroscopy and quantum physics.

Energy Levels

Energy levels, in the context of the Bohr model, refer to fixed or discrete states that electrons can occupy around an atom’s nucleus. Each level represents a specific amount of energy.
These levels are often thought of as rungs on a ladder. An electron can only stand on one rung at a time, never in between. Energy levels are quantized, meaning electrons can only exist in these distinct states.

• Higher-energy levels are further from the nucleus.
• Lower-energy levels are closer to the nucleus and have less potential energy associated with them.

This quantization has profound implications. It means that electrons must move in specific, allowed steps or transitions. Such movements are responsible for the absorption and emission of energy that can be detected and measured in experiments.

Quantum Theory

Quantum theory provides the framework necessary to understand the behavior of electrons in atoms, especially their transitions between energy levels.
According to quantum theory, electron behavior is not continuous but exists in quantized states, much like stepping stones rather than a ramp. This theory explains why only specific amounts of energy can be absorbed or emitted as electrons move between different energy levels.
Additionally, quantum theory introduces the concept of photons, which are quanta or packets of light energy. Electrons absorb or emit these photons when transitioning between energy levels.

• This theory clarifies why electron jumps can only happen when the exact energy difference is matched by a photon.
• It underscores the particle-wave duality nature of electrons, where they exhibit both particle-like and wave-like properties.

Quantum theory is pivotal in understanding atomic and subatomic processes, shaping much of modern physics and chemistry.