For homonuclear A A bonds, Linus Pauling took the covalent radius to be half the single-bond length in the element, e . g . " R " ( H & ndash; H, in H 2 ) = 74.14 pm so " r " cov ( H ) = 37.07 pm : in practice, it is usual to obtain an average value from a variety of covalent compounds, although the difference is usually small.
