Counting Atoms In Molecules - Worksheet Answers printable pdf download

Counting Atoms In Molecules - Worksheet Answers

Solutions

SNC2P Worksheet

Name _____________________________

Counting Atoms In Molecules

Date ____________________

Page # __________________

1.! The symbol of an element represents one atom of that element.

! e.g., Ca = calcium

2.! A subscript is a number written at the lower right corner behind the symbol of an element.

If there is more than one atom of the element in the molecule, then a subscript is used to indi-

cate the number of atoms.

! e.g., N

2 atoms of nitrogen

3.! A subscript outside a bracket multiplies all the elements inside the brackets.

! e.g., Ba

(PO

)

3 atoms of barium, 2 atoms of phosphorous, 8 atoms of oxygen

4.! a)! A coefﬁcient is a number written in front of a chemical symbol and indicates the number

of atoms of that element.

! ! e.g., 3C = 3 atoms of carbon

! ! or

! b)!A coefﬁcient is a number written in front of a chemical formula and indicates the number

of molecules of that compound.

! ! Note: A coefﬁcient multiples the number of atoms of each element in the formula.

! ! e.g., 2H

O =

4 atoms of hydrogen, 2 atoms of oxygen

! ! ! 3FeSO

3 atoms of iron, 3 atoms of sulfur, 12 atoms of oxygen

! ! ! 4Cu(NO

)

= 4 atoms of carbon, 8 atoms of nitrogen, 24 atoms of oxygen

PTO

Counting Atoms In Molecules - Worksheet Answers