Consider a sample of hydrogen gas in the glass discharge tube. The electric current is passed through the hydrogen gas present in the discharge tube under low pressure. When the hydrogen atoms absorb energy from the electric discharge, they get excited to higher energy states. And the unsettled electron in the excited state then returns to its initial position with the emission of photons of suitable wavelengths. Now, the hydrogen gas in the discharge tube glows red indicating, the electron transition between the two different energy levels. And the emitted light radiation is passed through the slit and made to fall on the glass prism that separates the light radiation into constituent wavelengths. Finally, the photographic plate placed over there records the line emission spectrum of hydrogen. The spectrum contains a set of lines in the ultraviolet, visible, and infrared regions. And the wavelength of lines obtained below 400 nm falls in the ultraviolet part of the electromagnetic spectrum. Similarly, wavelengths of lines obtained above 700 nm are in the infrared zone. The spectral lines in the visible region have wavelengths between 400-700 nm. The different wavelengths of light energy produced by hydrogen atoms are also known as the hydrogen light spectrum.

1. Hydrogen emission
spectrum
By
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2. Spectrum
Spectrum is an arrangement of radiations of various wavelengths
obtained by passing polychromatic radiation through the prism.
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3. Hydrogen Spectrum
The pattern of spectral lines given by the hydrogen atom in the
electromagnetic region due to the transition of electrons is called
the hydrogen spectrum.
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4. Types of Hydrogen Spectrum
The hydrogen spectrum is of two
types:
1. Hydrogen emission spectrum
2. Hydrogen absorption
spectrum
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5. Hydrogen Emission Spectrum
It is a specimen of bright lines obtained by passing emitted polychromatic
light radiations of the excited hydrogen atom through the prism.
It consists of bright lines on continuous spectrum of black background
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6. Hydrogen absorption Spectrum
It is a pattern of dark lines obtained by transmitting an absorbing
polychromatic light radiations of the ground state hydrogen atom
through the prism.
It consists of dark lines on continuous spectrum of white background
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7. Experimental set up for the hydrogen emission
spectrum
 Consider a sample of hydrogen gas in the
discharge tube.
 The electric current is passed through the
hydrogen gas present in the discharge tube
under low pressure.
 When the hydrogen atoms absorb energy from
the electric discharge, they get excited to higher
energy states.
 And the unsettled electron in the excited state
returns to its initial position with the emission
of photons of suitable wavelengths.
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8. Experimental set up for the hydrogen absorption
spectrum
 Consider a sample of hydrogen gas in the
discharge tube.
 A white light passes through the
hydrogen gas in present in the discharge
tube.
 And the transmitted light then passes
through the spectroscope gives a
spectrum of dark lines at definite
wavelengths.
 These dark lines correspond to the
wavelengths of light radiations absorbed
by the hydrogen atoms. Jayam chemistry learners

9. Overview of the Hydrogen Spectrum
 The pattern of spectral lines observed in both the emission and
absorption spectrums of hydrogen are identical at the same
temperature.
 These spectral lines occur in the ultraviolet, visible, and infrared
regions of the electromagnetic spectrum.
 The different wavelengths of light energy produced by hydrogen
atoms is known as the hydrogen light spectrum.
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10. Overview of the Hydrogen Spectrum
In the visible zone, four different
spectral lines observed at
wavelengths 656 nm, 486 nm, 434 nm,
and 410 nm give characteristic red,
aqua, blue and violet colored lines in
the visible emission spectrum of
hydrogen. It is known as the hydrogen
color spectrum. Jayam chemistry learners

11. Overview of the Hydrogen Spectrum
• The colored spectral emissions in
the visible region are noticeable
to the human eye.
• Besides, special spectrographic
techniques are essential to
observe the spectral lines in the
ultraviolet and infrared regions.
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12. The Hydrogen Line Spectrum
• The absorption of electric energy
excites the hydrogen electron from
the ground state to one of the higher
energy orbits.
• After being unstable, the electron
bounces back to its initial position
abruptly with the emission of
photons of discrete frequencies.
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13. The Hydrogen Line Spectrum
• These individually distinct spectral lines
relate to the sporadic photon emissions
by the energy quantization principle
mentioned by Bohr.
• Hence, the hydrogen spectrum is
discontinuous with a series of sharp
lines separated by dark bands is also
known as a line spectrum.
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14. Name the series of the Hydrogen Spectrum
The hydrogen spectrum has six series
named by the scientists who discovered
them. They are;
• Lyman series
• Balmer series
• Paschen series
• Brackett series
• Pfund series
• Humphreys series Jayam chemistry learners

15. Applications of the Hydrogen Spectrum
• Many street lights use bulbs that
contain sodium or mercury vapor.
• For sodium, the emission lines at 450
nm give characteristic yellow light.
• For mercury, blue colored light
observed due to spectral emissions at
589 nm
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16. Applications of the Hydrogen Spectrum
• Each atom has its characteristic
emission and absorption spectra.
• It serve as a fingerprint to
characterize them.
• It helps in the identification of
new substances in the universe.
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17. The end
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