Question

What is the formula for manganese(IV) oxide?

Answer 1

Hint :Manganese(IV) oxide is commonly known as manganese dioxide. It is considered to be a strong oxidizing agent and it reacts violently with the flammables, combustibles, and also with other reducing agents. It also decomposes other oxidants like potassium chlorate catalytically.

Complete Step By Step Answer:
As the name suggests, the given compound manganese(IV) oxide comprises a metal and a nonmetal. We know that any compound containing a metal and a non-metal is considered to be an ionic compound. In ionic compounds, we have to take into account the charges of each of the elements present in the compound. Now let us identify the formula for the given compound i.e. manganese(IV) oxide. Manganese(IV) oxide possesses a non-metal (oxygen in this case) after the metal (manganese) so we'll use a Periodic Table to identify the charge and symbol. Rules to write formula of an ionic compound are listed below:
1. Using the periodic table, write down the symbol for the metal along with its charge.
In the present case, the symbol of metal manganese (a transition metal) is $Mn$ having a charge +4 (Roman Numeral given in parentheses).
2. Using the periodic table again, identify the symbol as well as charge of the non-metal.
In the present case, non-metal is oxygen having a symbol $O$ having a charge -2.
3. Check if the charges are balanced
In the present case it becomes $M{n}^{4+}{O}^{2-}$ . The charges are not balanced as summation of charges is non-zero i.e. $(+4)+(-2)=+2\ne 0$
4. If unbalanced charges are there, add subscripts following the criss-cross method such that net charge for the compound is zero.
In the present case, we will add subscripts to both metal and non-metal such that the net charge becomes zero. So it becomes $(M{n}^{4+}{)}_2(O^{2-}{)}_4=(M{n}^{4+}{)}_{{\displaystyle \frac{2}{2}}}(O^{2-}{)}_{{\displaystyle \frac{4}{2}}}=(M{n}^{4+}{)}_1(O^{2-}{)}_2$ and now the net charge is balanced i.e. $(1\times (+4))+(2\times (-2))=0$
Hence, the chemical formula for calcium bisulphate is $Mn{O}_2$ .

Note :
While writing the chemical formula of an ionic compound, never write the subscript '1'. And it should be noted that we can also have two polyatomic ions like $N{H}_{4}N{O}_3$ in the same compound. In this case, we have to find and write both of the names as identified from the Common Ion Table.