Beanium Isotope Lab Chemistry

102 W10-Stoichiometry-and-LR

● 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

Materials: Plastic cup or ziplock bags of beans (black, brown, & white); electronic balance

Procedure:

  1. Obtain a plastic cup which contains many atoms (beans) of BEANIUM.
  2. Sort the atoms (beans) into a group for each isotope: black, brown, white. Record the total number of atoms and the number of each type of isotope (blackium, brownium, and whitium) in the data table.
  3. Determine the isotopic mass: a) find the total mass of each of the three isotope groups and record on data table b) find the average mass of a single atom of each isotope and record on the data table to the nearest 0.

EXAMPLE: I counted 340 white beans. They have a mass of 80 grams. The average mass of one white bean is 80 / 340 = 0 grams.

  1. Find the isotopic abundance (% of beans) for each isotope by dividing the number of atoms of one isotope by the total number of atoms (black, brown, plus white) and multiplying by 100%. Record on the data table to the nearest 0%.

EXAMPLE: There are a total of 500 atoms. 340 are white beans. Therefore, (340 ÷ 500) x 100% = 68% are white beans (whitium).

  1. Determine the atomic mass for BEANIUM based on the isotopic abundances and the isotopic masses.

FORMULA TO CALCULATE ATOMIC MASS = (blackium %) x (mass of one

blackium atom) + (brownium %) x (mass of one brownium atom) + (whitium %)

x (mass of one whitium atom)

  1. Place all the beans back in the plastic cup or ziplock bag.

Data:

● Show one sample of each calculation. Remember significant digits for all calculations. ● Complete the data table.

DATA TABLE

Isotope information: Total number of bean element atoms in cup = 345

13.

ISOTOPE # OF BEANS (ATOMS)

MASS OF BEANS (ATOMS)

AVERAGE MASS OF 1 BEAN (GRAMS)

170 36 3 2.

100 30 3 3.

75 21 3 4.

Calculations for atomic mass of BEANIUM . (use the data table to complete)

% of blackiumxmass + % of browniumx mass + % of whitiumxmass = Atomic mass “atoms” of blackium “atoms of brownium “atoms” of whitium of BEANIUM

x g + x g + x g = g 72=blackium 103=brownium 100=whitium