Question
Chemistry Question on GROUP 1 ELEMENTS
The alkali metals form salt-like hydrides by the direct synthesis at elevated temperature. The thermal stability of these hydrides decreases in which of the following order?
A
NaH > LiH > KH > RbH > CsH
B
LiH > NaH > KH > RbH > CsH
C
CsH > RbH > KH > NaH > LiH
D
KH > NaH > LiH > CsH > RbH
Answer
LiH > NaH > KH > RbH > CsH
Explanation
Solution
As the size of alkali metal ion increases, lattice enthalpy decreases and hence the stability of the corresponding metal hydride decreases.