Question

Amongst the following, the total number of species NOT having eight electrons around central atom in its outer most shell, is NH₃, AICI₃, BeCl₂, CCl₄, PCI₅ :

• A. 2
• B. 4
• C. 1
• D. 3

Answer 1

The Correct Option is D

To determine the total number of species that do NOT have eight electrons around the central atom in its outermost shell, we need to analyze each given compound based on the octet rule. The octet rule states that atoms tend to have eight electrons in their valence shell to achieve stability, similar to noble gases. Let's examine each compound:

1. NH₃ (Ammonia):

   Nitrogen in NH₃ has 5 valence electrons and forms three covalent bonds with hydrogen atoms, sharing a total of 3 additional electrons. Thus, around the nitrogen, there are 8 electrons fulfilling the octet.

2. AlCl₃ (Aluminum Chloride):

   Aluminum has 3 valence electrons and forms three bonds with chlorine atoms, resulting in only 6 electrons around the aluminum. Thus, AlCl₃ does not complete the octet around aluminum.

3. BeCl₂ (Beryllium Chloride):

   Beryllium has 2 valence electrons and forms two bonds with chlorine atoms, sharing only 2 additional electrons. Therefore, it has only 4 electrons around the beryllium center, not fulfilling the octet rule.

4. CCl₄ (Carbon Tetrachloride):

   Carbon has 4 valence electrons and forms four covalent bonds with chlorine atoms, thus sharing 4 additional electrons, totaling 8 electrons around carbon. This fulfills the octet rule.

5. PCl₅ (Phosphorus Pentachloride):

   Phosphorus has 5 valence electrons and forms five covalent bonds with chlorine atoms. Phosphorus shares 5 additional electrons (one from each chlorine), resulting in 10 electrons in its valence shell, which exceeds the octet rule. However, it does not satisfy the "eight electrons" part of the rule.

Upon reviewing the above compounds, it is observed that AlCl₃, BeCl₂, and PCl₅ do not have eight electrons around their central atom (Al, Be, and P, respectively) in their outermost shell.

Conclusion: The number of species not having eight electrons around the central atom in their outermost shell is 3.

Thus, the correct answer is: 3.