[填空题]
Calcium phosphide is used in explosives and fireworks.
1.Describe the bonding that exists between calcium and phosphorous in calcium phosphide.
2.State the chemical formula for calcium phosphide.
3.Calcium can also bond with thiocyanate to form calcium thiocyanate,($Ca(SCN)_2$). Deduce the ion charge on thiocyanate.
4.Calcium compounds usually exist as a crystal lattice in the solid state. Describe what the lattice enthalpy can reveal about the bonds in the compound, referring to the magnitude of the lattice enthalpy in the answer.
5.Calcium fluoride ($CaF_2$) and calcium oxide
(CaO) are two examples of ionic compounds of calcium. Choose the lattice enthalpy of CaO is than the lattice enthalpy of $CaF_2$
6.Predict, whether calcium oxide (CaO) or calcium fluoride ($CaF_2$)
will have a melting point.
