CBSE Class 11 Chemistry Structure Of Atom Notes Set A

13. o Emission spectrum: The spectrum of radiation emitted by a substance that has absorbed energy is called an emission spectrum.

14. o Absorption spectrum : The spectrum obtained when radiation is passed through a sample of material. The sample absorbs radiation of certain wavelengths. The wavelengths which are absorbed are missing and come as dark lines.

15. Bohr’s model for hydrogen atom:

a.An electron in the hydrogen atom can move around the nucleus in a circular path of fixed radius and energy. These paths are called orbits orenergy levels. These orbits are arranged concentrically around the nucleus.

b. As long as an electron remains in a particular orbit, it does not lose or gain energy and its energy remains constant.

c. When transition occurs between two stationary states that differ in energy, the frequency of the radiation absorbed or emitted can be calculated

d. An electron can move only in those orbits for which its angular momentum is an integral multiple of h/2π The radius of the nth orbit is given by r_n =52.9 pm x n²/Z

energy of electron in nth orbit is :

 

22. Bohr burry’s rule:- The lower the value of (n + l) for an orbital, the lower is its energy. If two orbitals have the same value of (n + l), the orbital with lower value of n will have the lower energy.

 

23. Degenerate orbitals The orbitals having the same energy are called degenerate orbitals.

 

24. Aufbau principle: electron filled in various subshell in increasing order of their energies.

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s……….

 

25. Pauli’s exclusion principle: No two electrons in an atom can have same set of four quantum numbers.

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