You just look at what vertical row that silicon is, and every element that is in the same vertical row as silicon will have the same lewis dot structure...and this applyes for most elements on the periodic table of elements.
- C, Ge,Sn, Pb:
all these elements are in the same column, and therefore have the same number of valence electrons
A clear chemical compound.
Number 1 is a synthesis reaction because two compounds/elements are coming together to form one compound
Al2(CrO4)3 = 401.9 grams per mole