The__ model assigns to fixed orbits of defined energy. To move between orbits, electrons must emit or absorb radiation

The Bohr model assigns to fixed orbits of defined energy. To move between orbits, electrons must emit or absorb electromagnetic radiation

Explanation:

In the Bohr model of the atom, the atom itself looks like a solar system.

In fact, at the center of the atom we have the nucleus, which contains protons and neutrons.

Around the nucleus, at a much higher distance, we have the electrons, negatively charged. The electrons move around the nucleus in fixed orbits, like the planets around the Sun.

According to Bohr's model, the electrons  cannot live in the space between two orbits, but they must stay in one of these orbits. Each of these orbits is associated to a certain energy level: therefore, this means that the energies of the electrons in an atom are quantized, so they cannot take all possible values, but only some precise values.

Moreover, according to the law of conservation of energy:

- When an electron jumps from a lower energy level to a higher energy level, it must absorbs energy, and this energy is absorbed in the form of electromagnetic radiation (a photon) whose energy is equal to the difference in energy between the two levels

- SImilarly, when an electron jumps from a higher energy level to a lower energy level, it releases energy, in the  form of electromagnetic radiation (a photon) whose energy is equal to the difference in energy between the two levels.

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally