<Li> Polyhedral skeletal electron pair theory for cluster compounds, including transition metals and main group elements such as boron including Wade's rules for polyhedral cluster compounds, including transition metals and main group elements and mixtures thereof . </Li> <P> Atoms that do not obey their rule are called "electron - deficient" when they have too few electrons to achieve a noble gas configuration, or "hypervalent" when they have too many electrons . Since these compounds tend to be more reactive than compounds that obey their rule, electron counting is an important tool for identifying the reactivity of molecules . </P> <P> Two methods of electron counting are popular and both give the same result . </P> <Ul> <Li> The neutral counting approach assumes the molecule or fragment being studied consists of purely covalent bonds . It was popularized by Malcolm Green along with the L and X ligand notation . It is usually considered easier especially for low - valent transition metals . </Li> </Ul>

Does cl- and br- have the same number of electrons