What is the experimental evidence in support of the idea that electronic energies in an atom are quantized?
The line spectrum of any element has lines corresponding to definite wavelengths. Lines are obtained as a result of electronic transitions between the energy levels. Hence, the electrons in these levels have fixed energy, i.e., quantized values.
Out of electron and proton which one will have, a higher velocity to produce matter waves of the same wavelength? Explain it.
From de-Broglie equation, wavelength, $\lambda=\frac{h}{m v}$
For same wavelength for two different particles, i.e., electron and proton, $m_1 v_1=m_2 v_2$ ( $h$ is constant). Lesser the mass of the particle, greater will be the velocity. Hence, electron will have higher velocity.
A hypothetical electromagnetic wave is shown in figure. Find out the wavelength of the radiation.
Wavelength is the distance between two successive peaks or two successive throughs of a wave.
Therefore,
$$\begin{aligned} \lambda=4 \times 2.16 \mathrm{pm} & =8.64 \mathrm{~pm} \\ & =8.64 \times 10^{-12} \mathrm{~m} \quad\left[\because 1 \mathrm{pm}=10^{-12} \mathrm{~m}\right] \end{aligned}$$
Chlorophyll present in green leaves of plants absorbs light at $4.620 \times 10^{14} \mathrm{~Hz}$. Calculate the wavelength of radiation in nanometer. Which part of the electromagnetic spectrum does it belong to?
$$\begin{aligned} &\text { Wavelength, }\quad \lambda=\frac{C}{V} \end{aligned}$$
$$\begin{aligned} \text { Given, } \quad \text { frequency } \nu & =4.620 \times 10^{14} \mathrm{~Hz} \text { or } 4.620 \times 10^{14} \mathrm{~s}^{-1} \\ \lambda & =\frac{c}{v}=\frac{3 \times 10^8 \mathrm{~ms}^{-1}}{4.620 \times 10^{14} \mathrm{~s}^{-1}} \\ & =0.6494 \times 10^{-6} \mathrm{~m} \\ & =649.4 \mathrm{~nm}\quad \left[\because 1 \mathrm{~nm}=10^{-6} \mathrm{~m}\right] \end{aligned}$$
Thus, it belongs to visible region.
What is the difference between the terms orbit and orbital?
Difference between the terms orbit and orbital are as below
| Orbit | Orbital |
|---|---|
| An orbit is a well defined circular path around the nucleus in which the electrons revolve. | An orbital is the three dimensional space around the nucleus within which the probability of finding an electron is maximum (upto 90%). |
| All orbits are circular and disc like. |
Different orbitals have different shapes. |
| The concept of an orbit is not in accordance with the wave character of electrons with uncertainty principle. | The concept of an orbital is in accordance with the wave character of electrons and uncertainty principle. |
| The maximum number of electrons in any orbit is given by $$2 n^2$$ where $$n$$ is the number of the orbit. | The maximum number of electrons present in any orbital is two. |