Aleksza &Ruscher
NHHS-C-Chemistry
2013-14
Beanium/Beadium Activity: Isotopes and Atomic Mass
Adapted from: Mr. Faucher’s Honor’s Chemistry Website &
CHEMISTRY: A Study of Matter © 2004, GPB
NAME:___________________________________________________MOD:______
LAB PARTNERS:_____________________________________________________
Objectives:
 Determination of the isotopic mass for each atom of each Beanium/Beadium isotope
 Determination of the relative abundance of each Beanium/Beadium isotope
 Calculation of the atomic mass for Beanium/Beadium
 Relate the use of a model to simulate actual elements and their isotopes
Materials: Plastic cup, three types of beans/beads, balance, weigh boats and calculators
Pre-Lab: Define the following terms:
Average -
Atomic Mass –
Isotope –
Mass Number –
Neutrons –
Relative Abundance –
Weighted Average -
Introduction: A new element has been discovered and it is your responsibility to learn the
following about the element:
• the number of naturally occurring isotopes present in the element
• the percentage of each isotope present in your sample of the element
• the atomic mass of the element
Procedure:
 Obtain a sample of the element from your teacher and record its ID number above the
chart.
 Count the total number of atoms in your sample and record in the space labeled as
such beside the blank for the ID#.
 Separate the element into its different isotopes. Assign each isotope a letter to identify it
and record this letter in the first column of the chart.
 Count the number of atoms of each isotope and record in the second column of the
chart.
 Mass each isotope group of atoms and record in the third column under "Mass of
Isotope Group”.
 Calculate the average mass of one atom of that isotope (Mass of Isotope
Group/ # of atoms of that isotope) and record under "Average Mass of Isotope
Group."
 Calculate the percentage of each isotope present in your element (# of atoms of isotope/total
# of atoms in sample) and record in the last column of the chart.
DATA TABLE
ID NUMBER:______________________ TOTAL NUMBER OF ATOMS:________________
ISOTOPE
# of atoms in
Isotope Group
Mass of Isotope
Group
Average Mass
of Isotope
Group
Percentage of
Isotope Group
 On the back of this worksheet, determine the average atomic mass of your element
using this equation: Be sure to show your work!
Average atomic mass = (avg. mass of isotope)(%) + (avg. mass of isotope)(%) +
...
(Remember that % means "per 100". In a calculation, 50% becomes 50/100 or
0.50.)
 Give your element a name and symbol and record the information here.
Remember that this is a new element so you, as a scientist, get to name this element whatever you
want!
Element Name:
________
_ Symbol
____ Atomic Mass:__________
Post Lab Questions:
1. Why don’t we divide the sum of the relative masses by the number of different types of
isotopes to determine the Atomic Mass?
2. Describe how this lab (model) relates to elements and their isotopes (reality)?
3. What can you conclude from this lab, regarding isotopes?