In general, the more _ a metal has, the stronger its metallic bonds will be because ...

In general, The more valence electrons a metal has, the stronger its metallic bonds will be because Boron is a metalloid and is ionically bonded. it is too electronegative to release its valence electrons for metallic bonding. As a result, their valence electrons feel a stronger pull from the nucleus (a greater effective nuclear charge) and are less easily released for metallic bonding.