Formulas and Atom Counting - Questions

The Formulas and Atom Counting Concept Builder is comprised of 36 questions. The questions are organized into 12 different Question Groups and spread across three difficulty levels. Questions in the same group are rather similar to one another; they may include the same formulas with differing coefficients. The Concept Builder is coded to select at random a question from each group until a student is successful with that group of questions.

There are three difficulty levels that can be engaged in through the Concept Builder. Those three levels are differentiated as follows:
 

• Apprentice Difficulty Level: Question Groups 1-4 ... Each question includes only 1 formula with a coefficient. There are no parenthesis. Learners must count the number of atoms of two or three elements. 
• Master Difficulty Level I: Question Groups 5-8 ... Each question includes 2 formulas with coefficients in front of each. Several of the formulas include parenthesis. Learners must count the number of atoms of three elements. 
• Wizard Difficulty Level: Question Groups 9-12 ... Each question includes 3 formulas with coefficients in front of each. Several of the formulas include parenthesis. Learners must count the number of atoms of three to four elements. 

The questions from each group are shown below. Teachers are encouraged to view the questions in order to judge which difficulty levels are most appropriate for their classes. We recommend providing students two or more options. 

The Physics Classroom grants teachers and other users the right to print these questions for private use. Users are also granted the right to copy the text and modify it for their own use. However, this document should not be uploaded to other servers for distribution to and/or display by others. The Physics Classroom website should remain the only website or server from which the document is distributed or displayed. We also provide a PDF that teachers can use under the same conditions. We have included a link to the PDF near the bottom of this page.

 

Formulas and Atom Counting

  
Apprentice Difficulty Level
Question Group 1
Question 1
How many total atoms of each element are present in the following formulas?
 
3 CaCl₂
 
 
Question 2
How many total atoms of each element are present in the following formulas?
 
2 AlCl₃
 
 
Question 3
How many total atoms of each element are present in the following formulas?
 
4 Na₂O
 
 
 
 
Question Group 2
Question 4
How many total atoms of each element are present in the following formulas?
 
2 NH₃
 
 
Question 5
How many total atoms of each element are present in the following formulas?
 
2 PCl₅
 
 
Question 6
How many total atoms of each element are present in the following formulas?
 
3 CO₂
 
 
 
 
 
Question Group 3
Question 7
How many total atoms of each element are present in the following formulas?
 
2 H₂SO₄
 
 
Question 8
How many total atoms of each element are present in the following formulas?
 
3 Na₂CO₃
 
 
Question 9
How many total atoms of each element are present in the following formulas?
 
3 H₂CO₃
 
 
 
 
 
Question Group 4
Question 10
How many total atoms of each element are present in the following formulas?
 
4 KClO₃
 
 
Question 11
How many total atoms of each element are present in the following formulas?
 
3 NH₄Cl
 
 
Question 12
How many total atoms of each element are present in the following formulas?
 
5 Na₂SO₄

 
Master Difficulty Level
Question Group 5
Question 13
How many total atoms of each element are present in the following formulas?
 
2 H₂O +  3 CO₂
 
 
Question 14
How many total atoms of each element are present in the following formulas?
 
5 H₂O +  4 CO₂
 
 
Question 15
How many total atoms of each element are present in the following formulas?
 
 
4 H₂O +  3 CO₂
 
 
 
 
 
Question Group 6
Question 16
How many total atoms of each element are present in the following formulas?
 
3 H₂SO₄  +  5 H₂O
 
 
Question 17
How many total atoms of each element are present in the following formulas?
 
2 H₂SO₃  +  4 H₂O
 
 
Question 18
How many total atoms of each element are present in the following formulas?
 
5 H₂SO₄  +  2 H₂O
 
 
 
 
 
Question Group 7
Question 19
How many total atoms of each element are present in the following formulas?
 
2 Al₂(SO₄)₃  +  3 Al₂O₃
 
 
Question 20
How many total atoms of each element are present in the following formulas?
 
3 Al₂(SO₄)₃  +  5 Al₂O₃
 
 
Question 21
How many total atoms of each element are present in the following formulas?
 
4 Al₂(SO₄)₃  +  2 Al₂O₃
 
 
 
 
 
Question Group 8
Question 22
How many total atoms of each element are present in the following formulas?
 
2 Ca₃(PO₄)₂  +  5 CaO
 
 
Question 123
How many total atoms of each element are present in the following formulas?
 
3 Ca₃(PO₄)₂  +  4 CaO
 
 
Question 24
How many total atoms of each element are present in the following formulas?
 
4 Ca₃(PO₄)₂  +  2 CaO
 

 
Wizard Difficulty Level
Question Group 9
Question 25
How many total atoms of each element are present in the following formulas?
 
2 H₂O +  4 H₃PO₄  +  3 P₄O₁₀
 
 
Question 26
How many total atoms of each element are present in the following formulas?
 
3 H₂O +  2 H₃PO₄  +  4 P₄O₁₀
 
 
Question 27
How many total atoms of each element are present in the following formulas?
 
4 H₂O +  3 H₃PO₄  +  2 P₄O₁₀
 
 
 
 
 
Question Group 10
Question 28
How many total atoms of each element are present in the following formulas?
 
2 H₂SO₄  +  5 SO₂  +  4 H₂O₂
 
 
Question 29
How many total atoms of each element are present in the following formulas?
 
3 H₂SO₄  +  4 SO₂  +  5 H₂O₂
 
 
Question 30
How many total atoms of each element are present in the following formulas?
 
5 H₂SO₄  +  3 SO₂  +  2 H₂O₂
 
 
 
 
 
Question Group 11
Question 31
How many total atoms of each element are present in the following formulas?
 
4 CaCl₂  +  2 Ca(ClO₄)₂  +  5 Ca(OH)₂
 
 
Question 32
How many total atoms of each element are present in the following formulas?
 
3 CaCl₂  +  4 Ca(ClO₃)₂  +  2 Ca(OH)₂
 
 
Question 33
How many total atoms of each element are present in the following formulas?
 
5 CaCl₂  +  3 Ca(ClO₄)₂  +  4 Ca(OH)₂
 
 
 
 
 
Question Group 12
Question 34
How many total atoms of each element are present in the following formulas?
 
5 AlCl₃  +  2 Al₂(SO₄)₃  +  3 H₂SO₃
 
 
Question 35
How many total atoms of each element are present in the following formulas?
 
4 AlCl₃  +  3 Al₂(SO₃)₃  +  3 H₂SO₄
 
 
Question 36
How many total atoms of each element are present in the following formulas?
 
3 AlCl₃  +  4 Al₂(SO₄)₃  +  5 H₂SO₄