# Atomic Spectra

Definition of an atomic Spectra is; the spectrum of electromagnetic radiation produced or absorbed by an electron during transitions between different levels of energy within an atom. As the electron is excited from one energy level to another, it either emits or absorbs light from a particular wavelength. Collection of all these wavelengths of the atom in a given range of conditions, such as pressure, temperature, etc., is the atomic spectra of atoms. There are three kinds of atomic spectra, namely, emission spectra, absorption spectra and continuous spectra.

Atomic Spectra

## Characteristics of Atomic Spectra

There are various characteristics of atomic spectra, such as:

1. The atomic spectra should be a pure line spectrum.
2. It should be an emission band spectrum.
3. It should be an absorption line spectrum.
4. Also, it should be the absorption band spectrum.

### Rydberg’s Formula

In atomic physics, Rydberg’s equation calculates the wavelength of the spectral line in a wide range of chemical elements. The equation is a generalisation of the Balmer series for all atomic hydrogen transitions. It is a unit of energy, explained in terms of the ground-state energy of the electron in the Bohr model of the hydrogen atom. In cgs, where “me” is electron mass, “e” is the charge of the electron, h-bar, “Z” is the atomic number, and “n” is the principal quantum number of the electron state. It is easy to measure the spectral lines using the Rydberg formula.

The Rydberg’s Formula is:

$$\frac{1}{\lambda}=RZ^{2}(\frac{1}{{n’}^{2}}-\frac{1}{n^{2}})$$

Where,

R is the Rydberg constant (1.09737*107 m-1)

Î» is the wavelength of light

Z is the atomic number

n is the upper energy level

n’ is the lower energy level

Single-electron atoms such as hydrogen have spectral series of Z = 1.

### Atomic Spectroscopy

Atomic spectroscopy is a study of electromagnetic radiation that is absorbed or released from atoms. There are three kinds of atomic spectroscopy, they are;

Atomic emission spectroscopy: It requires the transition of energy from the ground to the excited state. Also, atomic emissions can explain this electronic transformation.

Atomic absorption spectroscopy: for absorption, there should be an identical energy variation between the lower and higher energy levels. The principle of atomic absorption spectroscopy uses the fact that free electrons emitted in an atomizer can absorb radiation at a specific frequency. It quantifies the absorption in gaseous state of ground-state atoms.

Atomic fluorescence spectroscopy: it is a combination of atomic emission and atomic absorption as it includes both excitation and de-excitation radiation.

### Uses of Atomic Spectroscopy

• It is used in the pharmaceutical industry to find traces of the materials used.
• It is useful for studying multidimensional elements.
• Also, it is useful as a tool to study the structure of atoms and molecules.
• It gives an accurate analytical method for finding components in a material that has an unknown chemical composition.
• It is applicable for identification of the spectral lines of materials used in metallurgy.
• Atomic spectroscopy is also useful for occupational and environmental monitoring.

Q.1. Explain how the atomic emission spectra occur and how they relate to the elements on the periodic table.

Answer. The electrons that drop from the higher energy levels to the lower energy levels in an atom release a photon with a specific wavelength, which generates the atomic emission spectrum. The energy levels in the atom are unique to each element on the periodic table. Therefore, the wavelength of the light emitted can help to determine which element has produced the light.

Q.2. How do the lines on the atomic spectrum relate to the transition of electrons between energy levels?

Answer. Atomic spectrum lines relate to electron transitions between the energy levels. If the electron drops in the energy level, aÂ photon emits resulting in the emission line and, when the electron absorbs a photon and increase in the energy level, an absorption line is visible on the spectrum.

Q.3. Why should atomic spectra be a pure line spectrum?

Answer. When atoms are excited, they emit light from specific wavelengths corresponding to different colours. And the emitted light is observed as a series of coloured lines with dark spaces in between. A series of coloured lines is known as a line or atomic spectra. Each element generates a unique set of spectral lines. Since no two elements generate the same spectral lines, the specific elements line spectrum can differentiate them. It may have either absorption or emission line spectrum based on whether the atom is light or another colliding electron.

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