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Structure of Atom

Short Answer Type

221.

What subshells are possible in n = 3 energy level?

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222. What is the lowest value of n that allows g orbitals to exist ?

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223.

Using s, p, d notations describe the orbital with the following quantum numbers :
(a) n = 1, l = 0,
(b) n = 3, l = 1,
(c) n = 4, l = 2,
(d) n = 4, l = 3.

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Long Answer Type

224.

State and explain Pauli's Exclusion Principle.

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Short Answer Type

225. Why Pauli’s exclusion principle is called exclusion principle?

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226. Why in the building of the atom, the filling of 4s orbital takes place before 3d orbital?

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Long Answer Type

227. Describe Aufbau Principle.

Aufbau Principle (Aufbau means building up): According to this principle, the electrons are filled in various orbitals in order of their increasing energies. Thus, an orbital with the lowest energy will be filled first. The energy of an orbital is determined by (n + l) rule as explained below:

(i) The orbital with the lower (n + l) value has lower energy. For example, 4s and 3d orbitals.

Thus, 4s orbital has a lower energy than 3d orbital, hence filled first.

(ii) When two orbitals possess the same value of (n +1), then orbital having lower value of n has lower energy. For example, 2p and 3s orbitals.

2p orbital 3s orbital
n = 2 n = 3
l = 1 l = 0
n + l = 3 n + l = 3
Thus, 2p orbital has a lower energy than 3s orbtial

(iii) The different orbitals in the increasing order of energies are:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s.
The order is diagrammatically represented as shown.

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228.

Discuss the shapes of s-orbitals.

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Short Answer Type

229. Give three points of difference between 1s and 2s orbitals.

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230.

The bromine atom possesses 35 electrons. It contains 6 electrons in 2p orbital, 6 electrons in 3p orbital and 5 electrons in 4p orbital. Which of these electron experiences the lowest effective nuclear charge?

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