The bonding types of hydrogen

The hydrogen atom can use its Is orbital to overlap with a valence orbital of another atom to form a covalent bond, as in the molecules listed in Table 11.1.2. The covalent radius of hydrogen is 37 pm. 

The hydrogen atom can gain an electron to form the hydride ion II with the helium electronic configuration 

The hydride anion II is expected to be very polarizable, and its size changes with the partner in the MH or MH2 compounds. The experimental values of the radius of H cover a rather wide range  

From NaH, which has the NaCl structure with cubic unit-cell parameter a = 488 pm, the radius of H has been calculated as 142 pm. 

The loss of an electron from a H atom to form H+ is an endothermic process  

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