The hydride ion H-has the same electron configuration as helium but is...
Hydrogen 1H : 1S1
Hydride: 1H- :1S2
Helium 2He : 1S2
Helium has two proton in it and it can stabilize 2 electrons. But, in hydrogen as one more electron enters and it becomes hydride ion, now one proton has to account for two electrons, the stability is affected. In hydride one proton cannot stabilize two electrons so structural deformity arises which leads to its reactivity.
Hence option (b) is correct.
View all questions of this test
The hydride ion H-has the same electron configuration as helium but is...
Explanation:
The hydride ion (H-) consists of one proton and two electrons. It has the same electron configuration as helium, which is 1s2. However, the hydride ion is much less stable compared to helium. This can be explained by the following points:
1. Size of hydride ion is small:
The size of an atom or ion is determined by the number of electrons and the effective nuclear charge. The effective nuclear charge is the positive charge experienced by an electron due to the attractive force of the nucleus. In the case of the hydride ion, there is only one proton in the nucleus, which creates a strong positive charge. This strong positive charge attracts the two electrons tightly, resulting in a small size for the hydride ion. The small size makes the hydride ion more unstable compared to helium.
2. Single positive charge on the proton must now control the 2 electrons:
In helium, there are two protons in the nucleus, which create a higher positive charge. This positive charge is balanced by the two electrons, resulting in a stable electron configuration. However, in the hydride ion, there is only one proton in the nucleus, which means that a single positive charge must now control the two electrons. This leads to a less stable electron configuration and makes the hydride ion less stable compared to helium.
3. Helium is a noble gas hence it is more stable and more reactive:
Helium is a noble gas, which means it has a full valence electron shell. This gives helium a high level of stability. On the other hand, the hydride ion does not have a full valence electron shell. It has two electrons in its valence shell, but it requires one more electron to complete the octet. This makes the hydride ion more reactive compared to helium.
Therefore, the correct option is B) Single positive charge on the proton must now control the 2 electrons. This explains why the hydride ion, despite having the same electron configuration as helium, is much less stable.
To make sure you are not studying endlessly, EduRev has designed JEE study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in JEE.