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precise lines in the emisssion of an element acquire individual wavelengths.

Every individual wavelength corresponds to a discrete amount of energy. 

 

This comes under the concept of QUANTINIZATION.
 

"QUANTINIZATION" refers to the theory that electromagnetic radiation is found in the form of discrete "parcels" or quanta.

 

A "photon" refers to a quantum of radiation.

 

a Photon's Wavelength (λ) and energy E are linked through the following equation:

 

E = hc/λ

 

WHERE:

h = Planck's constant = 6.63 x 10  J s (Joules per second)

 

v = frequency of the radiaiton

 

c= speed of light

 

E is inversely proportional to λ.

 

 

 

 

 

 

 

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Quantization of Energy

When energy is supplied to an atom electrons are excited (gain energy) from their lowest state. Electrons can only exist in certain fixed energy levels. When electrons return to the first level (n=1) the series of lines occcurs  in the ultraviolet region as this involves the largest energy change. The visible region spectrum is foremd by electrons dropping back to teh n=2 level and the first series in the infrared is due to electrons falling ot the n=3 level. The lines in the spectrum convrge becasue the energy levels themselves converge.

 

Emission spectra are produced when photons are emitted from atoms as excited electrons return to a lower energy level

Emission Spectra: Explained

Neils Bohr the Danish Physicist observed the emission spectrum of the hydrogen atom.

 

He suggested a theory based explanation for the existence of the spectrum with the utilization of classical mechanics.

 

The terms of his mdoel were as written.

 

1) THE HYDROGEN ATOM i(s made up of a positively charged particle known as the proton- this is located in its center; around this , there is a negatively charged particle named the electron which moves in a circular path or orbit. TDespiute the fact that there is no attraction between teh oppositely charged species there is still a force of attraction whcih is balance dby the accelereation of the electron whcih is moving at  a high velocity throughout its orbit.

 

Furthermore Bohr also suggested that each orbit has a definite energy; which is linked to it.

 

The enrgy of the lectron whcih is orbiting the positively charged center in a certain orbit, is either quantized or fixed.

 

The expression which models this information is : E = - RH(1/n^2)

 

where RH= Rydeberg constant = 2.18 x 10 ^-18 J

 

n= principal quantum number, whcih has positive integer values 1, 2, 3 and 4.... this depends solely on the orbit/ energy level which the electron inhabits.

Excited electrons...

When an electron in its ground state is excited (for example by subjecting it to an electrical discharge) it moves to a higher energy level and it stays in this excited state for a fraction of a second.

 

When the electron falls back down from the excited state to a lower energy level, it emits a photon. The term photon referes to a discretet amount of energy. THis photons corresponds to a certain wavelength λ, this depends on the energy fdifference between teh two energy levels (figure 1)

Figure one principles of the Bohr model of an atom with an excited electron

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