Which violate hunds rule

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Ab aap Whatsapp pe solutions paa saktey h, hum aapko message karenge. Ab aap Whatsapp pe solutions paa saktey h, hum aapko ping karenge. Study Materials. Why use Doubtnut? Instant Video Solutions. Request OTP. Updated On: Share This Video Whatsapp. Text Solution. Solution :. Oxygen has one more electron than nitrogen; as the orbitals are all half-filled, the new electron must pair up. According to the first rule, electrons always enter an empty orbital before they pair up.

Electrons are negatively charged and, as a result, they repel each other. Electrons tend to minimize repulsion by occupying their own orbitals, rather than sharing an orbital with another electron. Furthermore, quantum-mechanical calculations have shown that the electrons in singly occupied orbitals are less effectively screened or shielded from the nucleus.

Electron shielding is further discussed in the next section. For the second rule, unpaired electrons in singly occupied orbitals have the same spins. Technically speaking, the first electron in a sublevel could be either "spin-up" or "spin-down. To avoid confusion, scientists typically draw the first electron, and any other unpaired electron, in an orbital as "spin-up.

Consider the electron configuration for carbon atoms: 1s 2 2s 2 2p 2 : The two 2s electrons will occupy the same orbital, whereas the two 2p electrons will be in different orbital and aligned the same direction in accordance with Hund's rule. Consider also the electron configuration of oxygen. Oxygen has 8 electrons. The electron configuration can be written as 1s 2 2s 2 2p 4. To draw the orbital diagram, begin with the following observations: the first two electrons will pair up in the 1s orbital; the next two electrons will pair up in the 2s orbital.

That leaves 4 electrons, which must be placed in the 2p orbitals. Therefore, two p orbital get one electron and one will have two electrons. Hund's rule also stipulates that all of the unpaired electrons must have the same spin. In keeping with convention, the unpaired electrons are drawn as "spin-up", which gives Figure 1. When atoms come into contact with one another, it is the outermost electrons of these atoms, or valence shell, that will interact first.

An atom is least stable and therefore most reactive when its valence shell is not full.