Question

According to Lewis and Kossel approach ,which of the following molecule has complete octet of the central atom.
1)LiCl
2)BeH2
3)PCl5
4)CO2​

Answer 1

Answer:

According to Lewis and Kossel approach, which of the following molecules has complete octet of the central atom? a) Licl b) BeH2 c) BCl3 d) CO2.

Answer 2

The correct answer is option (4) CO₂

EXPLANATION :

• According to Lewis and kossel approach, the atoms of a compound try to attain the stable octet configuration of electrons in its valence shell by sharing or losing electrons.

(1) LiCl

Atomic Number or Lithium - 3

Electronic configuration - 2, 1

The atomic number of chlorine - 17

Electronic configuration - 2,2,6,2,7.

Lithium will lose its 1 electron to attain the stable configuration equal to the nearest noble gas, Helium (2)

Hence, it is an exception to the octet rule.

(2) BeH₂

Atomic Number of Beryllium = 4

Electronic configuration - 2,2

Two atoms of hydrogen form a covalent bond with one central beryllium atom.

Hence, Beryllium hydride is an exception to the octet rule.

(3) PCl₅

Number of valence electrons in phosphorus atom = 5

Number of valence electrons in chlorine atoms= 1

So, 5 chloride ions form single bonds with phosphorus atoms.

Thus, phosphorus expands its octet and does not obey the octet rule.

(4) CO₂

Valence electrons in Carbon atom = 4

Valence electrons in oxygen atoms = 6

So, 2 pairs of electrons are shared by both the atoms of Carbon and Oxygen.

Number of lone pair on each oxygen atom = 4

Number of lone pair on Carbon atom = 0

Therefore, the central atom in CO₂ follows the octet rule.

Hence, the correct answer is (4) CO₂

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