Bohr S Model Of Hydrogen Atom

The hydrogen spectrum consists of several series, each corresponding to different regions of the electromagnetic spectrum. These series are categorized based on the transitions of electrons in the hydrogen atom. The key series are: - Lyman series: This series corresponds to transitions where the electron falls to the energy level. These transitions emit ultraviolet (UV) light. - Balmer series: This series corresponds to transitions where the electron falls to the energy level. These transitions emit visible light, which is why the Balmer series is in the visible region of the spectrum. - Paschen series: This series corresponds to transitions where the electron falls to the energy level. These transitions emit infrared (IR) light. - P-fund series: This series corresponds to transitions where the electron falls to the energy level. These transitions also emit infrared light. Therefore, the Balmer series is the only series that lies in the visible region.

The element chromium (Cr) commonly shows a +6 oxidation state in its fluorides, specifically in chromium hexafluoride (CrF) . In this compound, chromium is in the +6 oxidation state. Other elements like Mo, Fe, and Mn generally do not exhibit a +6 oxidation state in their fluorides. Thus, the correct answer is Cr.

Concept: Energy levels:

Step 1: Find excited level.
Energy required from to is approx 12.75 eV.

Step 2: Number of lines.

Step 1: Understanding the Concept:
Niels Bohr's atomic model (1913) was a foundational step in quantum mechanics, combining classical physics with early quantum ideas to explain the emission spectrum of hydrogen. While highly successful for simple cases, it possessed fundamental limitations.
Step 2: Key Formula or Approach:
The approach involves reviewing the core postulates of Bohr's theory and its historical failures to identify the false statement among the options.
Step 3: Detailed Explanation:
Let's evaluate each statement:
- A) Applicable to 1 electron system: This is a true statement. Bohr's model perfectly predicts the spectral lines of the hydrogen atom and other hydrogen-like (single-electron) ions such as and .
- C) Electrons revolve in non-radiating orbits: This is a true statement. It is one of Bohr's primary postulates intended to overcome the classical flaw in Rutherford's model. Bohr proposed that as long as an electron remains in a specific, allowed stationary orbit, it does not emit electromagnetic radiation.
- D) Angular momentum is quantised: This is a true statement. Another core postulate of Bohr is that an electron can only revolve in those orbits where its angular momentum ( ) is an integral multiple of . This quantization is what leads to discrete energy levels.
- B) Applicable to multielectron system: This is the incorrect statement. The most significant failing of Bohr's model was its inability to explain the spectra of atoms containing more than one electron (like Helium or any heavier element). The model only considers the electrostatic attraction between the nucleus and one electron; it cannot account for the complex inter-electronic repulsions present in multi-electron systems.
Step 4: Final Answer:
The claim that the Bohr model is applicable to multi-electron systems is false.

Step 1: Understanding the Concept:
According to Bohr's model of the hydrogen atom, the velocity of an electron in a specific orbit is quantized. The velocity depends on the atomic number ( ) and the principal quantum number ( ) of the orbit.

Step 2: Key Formula or Approach:
The formula for the velocity of an electron in the Bohr orbit is given by:

Where is the velocity of the electron in the first orbit of hydrogen ( m/s).
This shows the direct proportionality:

Step 3: Detailed Explanation:
For a hydrogen atom, the atomic number .
Therefore, the velocity in the orbit is inversely proportional to :

Given that the velocity in the orbit ( ) is :

We need to find the velocity in the orbit ( ), let's call it .
Using the proportionality:

Substitute :



Step 4: Final Answer:
The velocity in the orbit is .