化學一問...........

Group
----------------I---II---III---IV---V---VI---VII----O
----------1-------------------H---------------------He
----------2---Li---Be--B---C---N---O---F----Ne
----------3---Na---Mg--Al--Si--P--S---Cl----Ar
period--4---K----Ca----------
c ) Carbon combines with element X to form a covalent compound with the formula CX2 .
i ) To which group does X belong ?
ii ) Draw an electron diagram for the compound , showing electrons in the outermost shells only .