Question

practice
calculating the number of atoms using parenthesis

• to find the total number of atoms, multiply the ________ by each element in the parenthesis.
• total atoms for this formula = _____

Explanation:

In chemical formulas like \(Al_2(SO_4)_3\), when there are parentheses, the sub - script outside the parentheses is multiplied by each element inside the parentheses. For \(Al_2(SO_4)_3\):

• The number of \(Al\) atoms: There is a sub - script \(2\) outside the parentheses for \(Al\), so there are \(2\) \(Al\) atoms.
• For the \(SO_4\) part inside the parentheses:
• The number of \(S\) atoms: The sub - script of \(S\) inside the parentheses is \(1\), and then multiplied by the sub - script \(3\) outside the parentheses, so there are \(1\times3 = 3\) \(S\) atoms.
• The number of \(O\) atoms: The sub - script of \(O\) inside the parentheses is \(4\), and then multiplied by the sub - script \(3\) outside the parentheses, so there are \(4\times3=12\) \(O\) atoms.

Answer:

• First blank: sub - script outside the parentheses
• Second blank: \(2 + 3+12=17\)