<P> Many metal silicides are known , most of which have formulae that can not be explained through simple appeals to valence : their bonding ranges from metallic to ionic and covalent . Some known stoichiometries are M Si , M Si , M Si , M Si , M Si , M Si , M Si , M Si , M Si , MSi , M Si , MSi , MSi , and MSi . They are structurally more similar to the borides than the carbides , in keeping with the diagonal relationship between boron and silicon , although the larger size of silicon than boron means that exact structural analogies are few and far between . The heats of formation of the silicides are usually similar to those of the borides and carbides of the same elements , but they usually melt at lower temperatures . Silicides are known for all stable elements in groups 1 -- 10 , with the exception of beryllium : in particular , uranium and the transition metals of groups 4 -- 10 show the widest range of stoichiometries . Except for copper , the metals in groups 11 -- 15 do not form silicides . Most instead form eutectic mixtures , although the heaviest post-transition metals mercury , thallium , lead , and bismuth are completely immiscible with liquid silicon . </P>
<P> Many metal silicides are known , most of which have formulae that can not be explained through simple appeals to valence : their bonding ranges from metallic to ionic and covalent . Some known stoichiometries are M Si , M Si , M Si , M Si , M Si , M Si , M Si , M Si , M Si , MSi , M Si , MSi , MSi , and MSi . They are structurally more similar to the borides than the carbides , in keeping with the diagonal relationship between boron and silicon , although the larger size of silicon than boron means that exact structural analogies are few and far between . The heats of formation of the silicides are usually similar to those of the borides and carbides of the same elements , but they usually melt at lower temperatures . Silicides are known for all stable elements in groups 1 -- 10 , with the exception of beryllium : in particular , uranium and the transition metals of groups 4 -- 10 show the widest range of stoichiometries . Except for copper , the metals in groups 11 -- 15 do not form silicides . Most instead form eutectic mixtures , although the heaviest post-transition metals mercury , thallium , lead , and bismuth are completely immiscible with liquid silicon . </P>
what type of bonding is present in si
what type of bonding is present in si
ranges from metallic to ionic and covalent
ranges from metallic to ionic and covalent