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Ch.3 - Molecules, Compounds & Chemical Equations
Chapter 3, Problem 24c

Determine the number of each type of atom in each formula. c. Al(NO3)3

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1
Step 1: Identify the different types of atoms in the formula. In Al(NO3)3, we have Aluminum (Al), Nitrogen (N), and Oxygen (O).
Step 2: Determine the number of each type of atom. For Aluminum (Al), there is no subscript following it, which means there is only 1 atom of Aluminum.
Step 3: For Nitrogen (N), it is inside the parentheses and followed by a subscript of 3 outside the parentheses. This means there are 3 atoms of Nitrogen.
Step 4: For Oxygen (O), it is also inside the parentheses and followed by a subscript of 3 inside the parentheses. However, the entire Nitrate ion (NO3) is also followed by a subscript of 3 outside the parentheses. This means there are 3*3 = 9 atoms of Oxygen.
Step 5: In summary, there is 1 atom of Aluminum, 3 atoms of Nitrogen, and 9 atoms of Oxygen in the formula Al(NO3)3.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chemical Formula Interpretation

A chemical formula represents the types and numbers of atoms in a compound. In the formula Al(NO3)3, 'Al' stands for aluminum, and 'NO3' represents the nitrate ion. The subscript '3' indicates that there are three nitrate ions associated with one aluminum atom.
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Understanding Polyatomic Ions

Polyatomic ions are charged entities composed of two or more atoms covalently bonded. In this case, the nitrate ion (NO3-) is a common polyatomic ion. Recognizing these ions is crucial for accurately counting the atoms in a compound, as they often appear in multiples.
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Counting Atoms in Compounds

To determine the number of each type of atom in a compound, one must account for both the elements and their respective quantities indicated by subscripts. For Al(NO3)3, there is one aluminum atom, and since there are three nitrate ions, each containing one nitrogen and three oxygen atoms, the total counts are one Al, three N, and nine O.
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