Skittlurium Isotope Lab
Name:
Purpose: To be able to calculate the average atomic mass of the element “Skittlurium”.
Materials:
 Paper cup (for massing)
 Sample of Skittlurium
 Analytical balance
 Calculator
Pre-Lab
What is an isotope?
What do the skittles represent?
What does each color of the skittle represent?
How many isotopes of skittles are there?
Procedure:
1. Determine the total quantity of Skittlurium atoms you have in your sample. (All the
skittles you have!)
2. Count out the number of each isotope. (An isotope is defined as elements that have the
same atomic number yet have difference masses. Skittlurium’s isotopes are differentiated by
color.)
3. Determine the mass of each isotope. (Mass of all the green isotopes, etc.)
Data:
Total number of atoms: ____________
Color of
Isotope
Number of
“atoms” of
each
isotope
Total mass
of isotope
sample (g)
Number of
“atoms”
CLASS
Total Mass
CLASS
Analysis:
 Calculate the percent abundance of each isotope.
To do this take the total quantity of each isotope (color), divide by the quantity of all skittlurium atoms and
multiple by 100. Report your percentage to the nearest hundredth. For example, if you had 5 red skittles
and 20 total skittles you would: (5/20) x 100 = 25.00. Percent abundance of the red isotope is 25.00%
 Calculate the average mass of each isotope.
To do this, take the total mass of each isotope (color) divide by the quantity of that isotope. Example, if
the mass of the red isotope of skittles is 2.5 g, then 2.5g/5 = 0.5g. Average mass of red isotope = 0.5 g.
 Calculate the average atomic mass.
Use the following formula and don’t forget order of operations!
(% Abundancegreen /100) x Avg.Massgreen + (%Abundancepurple/100 x Avg.Masspurple + (Abundanceorange /100) x Avg.Massorange +
(Abundanceyellow /100) x Avg.Massyellow + (Abundancered /100) x Avg.Massred = Average Atomic Mass