Explain when and why parentheses are necessary when writing chemical formulas that include polyatomic ions. Provide an example with your explanation. Make sure to discuss how removing the
parentheses from your example would change the readers understanding of the formula.

- the 2 in this formula is called the subscript. It refers only to the  element preceding it. In this case the F (fluorine).  

- in some chemical formulas it is necessary to use parentheses. The  subscript outside the parentheses refers to all the elements inside  the parentheses. In this example there are: one Al (aluminum), three  N (nitrogen), and nine O (oxygen).

- the 3 in this formula is called the coefficient. It refers to each  element that follows. In this case there would be 3 Ba (barium) and 3  F2 (a total of 6 fluorine).

Explanation:

samuel de champlain. in 1608, king henry iv sponsored pierre dugua, sieur de mons and samuel de champlain as founders of the city of quebec with 28 men. this was the second permanent french settlement in the colony of canada.

- decrease the number of plants and animals living in the water.