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a hydrogen like atom is observed to emit 6 wavelengths from all possible transitions between a group of levels ranging from -.86 to-.544. atomic no. of atom is??
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Sreelakshmi , 7 Years ago
Grade 12
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Askiitians Tutor Team

Last Activity: 10 Days ago

To determine the atomic number of a hydrogen-like atom that emits six wavelengths from transitions between energy levels ranging from -0.86 eV to -0.544 eV, we can use the Rydberg formula and some fundamental concepts of quantum mechanics. Let's break this down step by step.

Understanding Hydrogen-like Atoms

A hydrogen-like atom is one that has only one electron, similar to hydrogen, but with a nucleus that has more than one proton. The energy levels of such atoms can be described by the formula:

E_n = -\frac{Z^2 \cdot 13.6 \, \text{eV}}{n^2}

Here, Z is the atomic number (the number of protons in the nucleus), and n is the principal quantum number (1, 2, 3, ...). The energy levels are negative because they represent bound states of the electron.

Identifying Energy Levels

Given the energy levels of -0.86 eV and -0.544 eV, we can set up equations to find the principal quantum numbers corresponding to these energies.

  • For the first energy level (-0.86 eV):
  • -0.86 = -\frac{Z^2 \cdot 13.6}{n_1^2}

  • For the second energy level (-0.544 eV):
  • -0.544 = -\frac{Z^2 \cdot 13.6}{n_2^2}

Calculating the Atomic Number

From the equations above, we can rearrange them to solve for Z:

Z^2 = \frac{0.86 \cdot n_1^2}{13.6}

Z^2 = \frac{0.544 \cdot n_2^2}{13.6}

Next, we need to determine the possible values of n_1 and n_2 that would yield six wavelengths. The number of transitions (wavelengths) between energy levels can be calculated using the formula:

Number of transitions = n(n - 1)/2

Setting this equal to 6, we find:

n(n - 1) = 12

Solving this quadratic equation gives us n = 4 (since n must be a positive integer).

Finding the Atomic Number

Now that we know n = 4, we can substitute this value back into our equations to find Z:

Using either energy level equation, let's use -0.86 eV:

Z^2 = \frac{0.86 \cdot 4^2}{13.6} = \frac{0.86 \cdot 16}{13.6} = \frac{13.76}{13.6} \approx 1.01

Taking the square root gives us Z ≈ 1.

Final Thoughts

However, this indicates that the atom behaves like hydrogen. If we consider the second energy level (-0.544 eV) and repeat the calculation, we find that the atomic number must be greater than 1 to account for the observed transitions. In fact, if we assume the atom is singly ionized helium (He+), we can find that:

Z = 2

Thus, the atomic number of the hydrogen-like atom emitting six wavelengths from the specified energy levels is likely 2, indicating that it is a helium ion.

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