Question

Formula for $C{d^{2 + }}$ and $PO_4^{3 - }$ . Also what is its name?

Answer 1

Hint : When any two ions of opposite charge are given, they usually form a compound together by criss- cross method. In this method, the charge of one ion becomes the subscript for the other ion. This is another way to write the chemical names of the compounds.

Complete Step By Step Answer:
Two oppositely charged ions are given in the question. One is $C{d^{ + 2}}$ which is Cadmium ion and the other one is $PO_4^{3 - }$ , which is phosphate ion. When there are two oppositely charged particles, they always tend to attract and form a compound because we know that unlike charges attract and like charges repel. Here, a criss-cross method is followed where the charge of Cadmium ion becomes the subscript for Phosphate ion and the charge of phosphate ion becomes the subscript for Cadmium ion. As a result, it forms $C{d_3}{\left( {P{O_4}} \right)_2}$ . The chemical formula of this compound is Cadmium phosphate. This is an example of ionic compound because it is formed as a result of exchange of ions and these are typically neutral. Ions always combine in a way to neutralize their charges. In order to write the chemical formulas, we need to have an idea about the symbol of the elements and also the valence electrons present in them.

Note :
The other thing to remember is, you may be getting doubts as to why the above compound is named as Cadmium phosphate and why can’t it be phosphate cadmium. In any compound containing metal and a non metal, the metal name should always be followed by a non metal.