Question

1.An ionic compound made Mg and F must be M_gF₂. Why is this case? In your answer consider the charge on Mg and F, based on their potion in the periodic table.

2. The correct name for Cu²⁺ and Cl^- forming CuCl₂ is Copper (II) Chloride, however Ba²⁺ and Cl^- forming BaCl₂ is not written barium (II) Chloride (instead written as just barium chloride). Why? (Hint- think about where copper is in the periodic table.

3. Notice question 2 above, neither ionic compound is written as a dichloride, yet for covalent compounds it would be written that way (e.g. OF₂ is oxygen diflouride). Thi is because a metal cation has a certain charge, then the non metal anions have to combine in only one possible proportion but covalent compounds rely on sharing and can do so in multiple ways, so the number of elements is specified by prefixes (di, tri, tetra, etc.). The question is what is the name for P₂F₄?

Answer 1

1) The Mg is an alkaline earth metal and exists only in +2 oxidation state, being present in group 2 and the F being an halogen is always exists in -1 oxidation state (being the most electronegative element). The F belong to group 17

Hence to have a neutral compound. one mole of Mg reacts with two moles of F, hence the charge on Mg is +2 and charge on F is -1

Therefore, the compound is MgF2

2) Barium is always present in +2 oxidation sate since it belongs to the list of alkaline earth metal, hence it always combine in the formula of one unit of Ba with two units of Cl, hence the formula will be Barium Chloride (since it is always fixed that Barium will be having +2 oxidation state).

Cu exists in both oxidation state +1 and +2, hence it is required to specifically specify that Copper (II) chloride in order to differnetiate between CuCl and CuCl2

3) The name of compound P2F4 is diphosphorus tetraflouride (since two phosphorus atoms are combined with four flourine)