Which of the following formulas has the same number of Oxygen atoms?
1. 2H2SO4
2. 2C8H10N4O2
3. 3H2O2
4. 2CaSO4
Chemical formulas look complex, but they are really not. There are 3 parts to a chemical formula, the elements that make up the formula, the number of atoms of each element, and the number of molecules.
Elements-To determine the number of elements in a formula, count the capital letters. Example CO has two elements, and Co is only one element.
Subscript-the small number, in a chemical formula, that shows you the number of atoms of elements in molecule. Example: H
2O, the little 2 is the subscript and says there are 2 Hydrogen atoms. There is an understood subscript of 1 behind O that you do not write.
Determine the number of elements and the number of atoms of each element in the formulas below. The answers are in the table below, and there is a video tutorial below each answer.
NaCl
Mg2O
CuCO3
NaCl Mg2O CuCO3
# of elements(count the capital letters) __2____
Number of atoms of each element (look at subscripts)
Na-1 Cl-1
# of elements(count the capital letters) __2____
Number of atoms of each element (look at subscripts)
Mg- 2 O-1
# of elements(count the capital letters) _3_____
Number of atoms of each element (look at subscripts)
Cu-1, C-1, O-3
The number of molecules is determined by the big number (coefficient) that appears in front of the formula.
A coefficient is used as a multiplier to every subscript in the formula, including the formulas with an understood subscript of 1.
2H2O means I have 2 molecules of H2O. In 2 molecules of H2O, I have 4 atoms of H, and 2 atoms of O.
Determine the number of elements, the number of atoms of each element, and the number of molecules in the formulas below. The answers are in the table below, and there is a video tutorial below each answer.
2O2
3NaCO3
2Al2O3
2O2 3NaCO3 2Al2O3
# of elements _1_____
Number of atoms of each element
O-4
Number of total atoms ___4___
Number of molecules ___2___
# of elements ___3___
Number of atoms of each element
Na-3 C-3 O-9
Number of total atoms ___15___
Number of molecules __3____
# of elements ___2___
Number of atoms of each element
Al-4 O-6
Number of total atoms ___10___
Number of molecules __2____
When You Have Completed the Question Below, Click Next
Which of the following formulas has the same number of Oxygen atoms?
1. 2H2SO4
2. 2C8H10N4O2
3. 3H2O2
4. 2CaSO4
Formulas 1 and 4
None of the formulas have the same number of Oxygen atoms
Formulas 2 and 3
Formulas 2 and 4