Problem: Which of the following compounds is the most stable? PbH4 SiH4 GeH4 CH4 SnH4 

We’re being asked to identify the most stable compound. 

The stability of each compound can be related to their bond strength and bond length:

▪ the stronger the bonds, the closer or the smaller the distance between the atoms
▪ higher bond strength → shorter bond length 

To answer this, we're going to compare the atomic radius of the elements bonded to H:

Atomic radius represents the distance from the nucleus to the outer shell of an element. 

Trend of atomic radius in the periodic table:

• decreases going from left to right of a period

• increases going down a group