Bohr Model (Simplified): Videos & Practice Problems

The Bohr model of the atom presents a simplified view of atomic structure, where electrons orbit the nucleus in defined circular paths known as shells. These shells are designated by the variable n, which represents both the shell number and the corresponding energy level of the electrons. The potential energy of an electron is influenced by its position within these shells; thus, electrons in different shells exhibit varying potential energies.

In this model, the nucleus is composed of protons, which are positively charged, and neutrons, which carry no charge. The first shell, corresponding to n = 1, can hold a maximum of 2 electrons. The second shell, where n = 2, can accommodate up to 8 electrons. For example, in the first shell, there are 2 electrons, while the second shell contains 3 electrons in this illustration.

Understanding the arrangement of electrons in these shells is crucial, as it directly relates to their potential energy. The further an electron is from the nucleus, the higher its potential energy due to the increased distance from the positively charged protons. This relationship highlights the significance of the shell structure in determining the energy states of electrons within an atom.

In an atom, electrons occupy specific orbits or shells, and they can transition between these shells through the processes of absorption and emission of energy. Absorption occurs when an electron moves from a lower energy shell to a higher energy shell, while emission is the reverse process, where an electron transitions from a higher energy shell back to a lower energy shell.

During absorption, an electron absorbs energy from an external source, such as a photon, which allows it to jump from its initial shell to a higher energy state, known as the excited state. For example, an electron in the first shell can absorb energy and move to the third shell. Conversely, during emission, the electron releases the excess energy it previously absorbed, returning to its original position, or ground state. In this case, the electron would move from the third shell back down to the first shell.

The energy required for these transitions varies depending on the shells involved. As the shell number increases, the distance between the shells decreases. For instance, the energy needed to transition from shell 1 to shell 2 is greater than that required to move from shell 3 to shell 4. This is because the distance an electron must travel increases the energy needed for the transition. Therefore, the transition from shell 1 to shell 3 requires significantly more energy than moving from shell 3 to shell 5, as the latter involves a smaller distance.

In summary, the relationship between shell transitions and energy can be understood as follows: the greater the distance an electron must travel between shells, the more energy is required. Consequently, it is easier for an electron to transition between higher numbered shells, such as from shell 6 to shell 7, than it is to move from shell 1 to shell 2.