In this chapter, you are going to learn about atom and atoms collisions. Every particular substance in this universe is made up of atoms. Without atoms, there won’t be any substance. An atom is a tiny particle that cannot be seen by your naked eyes. The molecules collide(come into conflict) with the combination of kinetic energy to bring the chemical reaction; it is done in collision theory.
Let me give an example of the question:
Question 12.9: A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?
Solution 12.9: From the formula
En = ‒13.6/n2 eV
For n = 3 to n = 1
E3 – E1 = 12.09 eV or (near to) 12.5 eV
This energy difference includes both the Lyman and Balmer series.
At room temperature, most of the hydrogen atoms are in ground state. So, n = 1, and the energy difference indicates the final n to be 2 or 3.
For n = 2
(1/λ) = R [(1/12) ‒ (1/22)]
λ = 122 nm
For n = 3, 𝜆= 103 nm
For n = 3,
1/λ = R [(1/22) ‒ (1/32)]
⇒ λ = 656 nm.
This type of theory and problems you are going to learn in this ex 12.9 chapter 12 in class 12th physics.