Name _________________________                                                          Period _____

 

WORKSHEET -- INTERPRETING MOLECULAR FORMULAS

 

Purpose:  To be able to interpret molecular formulas by listing which elements and

            how many atoms of each element there are in a compound.

 

1.  What is a compound? __________________________________________________

            _______________________________________________________________

 

2.  Any chemical compound can be represented by a ____________________________

            _______________________________________________________________.

 

3.  Write the chemical formula for:

            a) water _________            b) salt __________            c) sugar __________________

 

4.  An element symbol with no number after it stands for _________________________

___________________________________________________________________.

            a) In CaO there are _____ atoms of calcium and _____ atoms of oxygen.

            b) In NaOH there are _____ atoms of sodium, _____ atoms of oxygen, and _____

                        atoms of hydrogen.

5.  A subscript after an element symbol means _________________________________

____________________________________________________________________.

            a) In MgCl₂ there are _____ atoms of magnesium and _____ atoms of chlorine.

            b) In H₂CO₃ there are _____ atoms of hydrogen, _____ atoms of carbon, and

                        _____ atoms of oxygen.

6.  A group of symbols surrounded by parentheses means that these elements are together as a unit.  A subscript outside the parenthesis means _____________________________

____________________________________________________________________.

            a) In Ca(NO₃)₂, the 2 means that _____________________________________.

                        so there are _____ atoms of Ca, _____ atoms of N, and _____ atoms of O.

            b)  In Mn(OH)₂ there are _____ atoms of Mn, _____ atoms of O, and _____

                        atoms of H.

7.  A number in front of a chemical formula means that there is more than one of that molecule.  For example, a 2 in front of CaO means that there are 2 molecules of CaO. (Twice as many Ca’s and twice as many O’s.)

            a) 2 NaOH means there are _____ atoms of Na, _____ atoms of O, and _____

                        atoms of H.

            b) 3 MgCl₂ means there are _____ atoms of Mg, and _____ atoms of Cl.

            c) 3 Mn(OH)₂ means there are _____ atoms of Mn, _____ atoms of O, and _____

                        atoms of H.

8.  Interpret the following molecular formulas.  List the number of atoms of each element.

            a) ZnO ___________________________________________________

            b) SO₂ ___________________________________________________

            c) 3 PbO₄ ___________________________________________________

            d) NaOH ___________________________________________________

            e) C₃H₅(OH)₃ ___________________________________________________

            f) C₂H₅ONa ___________________________________________________

            g) 2 Fe(OH)₃ ___________________________________________________

            h) CaSiO₃ ___________________________________________________

            i) H₃BO₃ ___________________________________________________

            j) KMnO₄ ___________________________________________________