The reaction of lithium and silicon at elevated temperatures gives a product of stoichiometry Li12Si7, which has been examined crystallographically and shown to be [Li+]24[Si56-]2[Si412-]. a) The [Si56-] ion possesses a cyclic structure (five membered ring). How many valence electrons does the [Si56-] anion as a whole have? b) The [Si412-] anion consists of a central silicon atom and three attached terminal silicon atoms. How many electrons are in the valence shell of the central silicon atom? What does VSEPR theory predict for the structure (show lone pairs on the central atom and terminal atoms, if any). c) The crystal structure of Li12Si7 shows that the [Si412-] anion adopts a planar triangular structure. Why do you think the anion adopts this structure? (Hint: what are the formal charges?)