Beanium Isotope Lab
Introduction & Purpose:
What is an isotope? What does it mean to say that the atoms in a sample of an element are
isotopes of each other? Ordinary beans are a lot bigger than atoms, but perhaps they can give
you one or two clues about isotopes.
We have talked in class about isotopes: atoms of the same element that differ in mass.
For example, there are actually three different kinds of hydrogen atoms. Refer to
the table below for the different kinds (or isotopes) of two common atoms.
ISOTOPE PROTONS ELECTRONS NEUTRONS SIGNIFICANCE
Protium 1 1 0 “normal” hydrogen
Deuterium 1 1 1 “heavy hydrogen”
Tritium 1 1 2 radioactive hydrogen
Carbon-12 6 6 6 “normal” carbon
Carbon-14 6 6 8 carbon-14 dating
This lab exercise is designed to show you isotopes of an element in a simulation form. You will be asked to gather
data about the “isotopes” and organize the data. If atoms were as large as beans they could be sorted, counted,
and massed. In this experiment we will sort, count, and mass three different kinds of beans and imagine that we
are observing three different isotopes of the same element (let’s call it BEANIUM). The three different isotopes
are blackium, brownium, greenium and whitium. Finally we will calculate the isotopic mass, the isotopic
abundance, and the atomic mass of the bean element.
These experiments and calculations are equivalent to the way scientists actually determine the atomic mass of
elements. As in real elements, the mixture of isotopes are collections of atoms of the element each having
different masses because they have different numbers of neutrons. Unlike real isotopes, the individual isotopic
particles of Beanium differ slightly in mass, so you will determine the average mass of each type of isotopic
particle. Then you can calculate the "weighted average atomic mass" of Beanium.
Definitions/ reference:
Isotopic mass – the average mass of the atoms of a specific isotope of an element
Isotopic abundance – what percent of the element’s atoms are a specific isotope
Atomic mass – the average mass of an element’s atoms
#Protons: determine which element an atom is – determines the atomic number
# electrons: determine the charge on an atom
Protons = electrons – atom is neutral
Protons> electrons – atom is positively charged (lost electrons)
Protons< electrons - atom is negatively charged (gained electrons)
# neutrons – determines the atomic mass of an atom. Determines the isotope number of the
atom.
Isotope: an atom of an element with a certain number of neutrons.
Beanium Lab
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