Macroscopic Atoms
In this lab activity, an analogy will be made between atoms and legos. The different colors of legos will
represent different elements; the tan legos will have an element symbol T, and the grey legos element
symbol G. The goal of this activity is to establish a familiarity with the concept of a mole and Avogadro’s
number (both of which attempt to quantify particles at the atomic scale that we can’t see), by working
with objects that we can visualize and see immediately before us.
CHEMISTRY WORLD
LEGO WORLD
In chemistry, 1 mole is defined to be the number In lego land, 1 lole is defined to be the number of
of atoms in 12 g of C-12. This is a useful, but legos in 12.06 g of G (grey legos). This will be the
arbitrary reference standard.
arbitrary reference standard for counting legos.
1 mole = Number of atoms in 12 g of C-12
With this definition, the mole specifies 6.022 x
1023 of any object in the chemical world:


1 mole of Mg
1 mole of Cl
= 6.022 x 1023 atoms of Mg
= 6.022 x 1023 atoms of Cl
Since each individual carbon atom has a different
mass from the magnesium or chlorine atoms, 1
mole of these elements will also have different
masses. The molar mass indicates the number of
grams present per mole (g/mol) of the chemical
substance:


Molar mass of Mg
Molar mass of Cl
= 24.30 g/mol
= 35.45 g/mol
1 lole = Number of legos in 12.06 g of G
Based on this definition, one lole specifies 28 of
any object in lego world:


1 lole of G
1 lole of T
= 28 grey legos
= 28 tan legos
Since each individual grey lego has a different mass
from the tan or blue legos, 1 lole of these legos will
also have different masses. The lolar mass
indicates the number of grams present per lole
(g/lol) of the substance:


Lolar mass of T
Lolar mass of G
= 9.77 g/lol
= 12.06 g/lol
CHEMISTRY WORLD
LEGO WORLD
1. Determine the total mass of magnesium (Mg)
provided in the small vial.
1. Determine the total mass of the tan legos (T)
provided in the small beaker.
Mass of Mg (g):_____________________________
Mass of T (g): _____________________________
2. Using the molar mass of Mg as a conversion
factor, calculate the number of moles of Mg
present in Step 1 above.
2. Using the lolar mass of T as a conversion factor,
calculate the number of loles of T in Step 1
above.
Moles of Mg:
Loles of T:
3. Using Avogadro’s number as a conversion
factor, calculate the number of atoms of Mg
present in the number of moles from Step 2
above.
3. Using “Legogadro’s” number (1 lol = 28 legos) as
a conversion factor, calculate the number of tan
legos (T) present in the number of loles from
Step 2 above.
Number of Mg atoms:
Number of T legos:
4. Consider the chemical reaction below: One
atom of magnesium (Mg) combines with two
atoms of chlorine (Cl) to form the ionic
compound magnesium chloride (MgCl2):
4. Consider the lego reaction below: One tan lego
(T) combines with two grey legos (G) to form a
lego compound of TG2:
Mg + Cl2 → MgCl2
Following the chemical reaction above, how many
chlorine atoms (Cl) would be needed to combine
with the amount of magnesium you weighed out in
Step 1? Convert this to moles of chlorine atoms.
Number of Cl atoms:
Number of moles of Cl atoms:
T + 2 G → TG2
Following the lego reaction above, how many grey
blocks (G) would be needed to combine with the
amount of tan blocks you weighed out in Step 1?
Convert this to loles of grey legos.
Number of G legos:
Number of loles G legos:
5. Using the molar mass of Cl as a conversion
factor, how many grams of Cl atoms would
combine with the Mg from Step 1?
5. Using the lolar mas of G as a conversion factor,
how many grams of G would combine with the
T from Step 1?
Mass of Cl (g):
Mass of G (g):
Summary of Steps 1-5:
A sample of magnesium (Mg) was weighed. Using
relative atomic masses, the mass of chlorine (Cl)
needed to combine with this magnesium (Mg) to
form MgCl2 was calculated.
Summary of Steps 1-5:
A sample of tan legos (T) was weighed. Using the
relative mass of the legos, the mass of grey legos
(G) needed to combine with these tan legos (T) to
form TG2 was calculated.
6. Now weigh out the mass of grey legos (G) you calculated in Step 5 above. Using this sample of G,
connect them to the tan legos you weighed (from Step 1) to form lego molecules with the formula
TG2.

Did you have the right number of each lego to fully form TG2 without any legos leftover
unreacted?
7. Of course, we could have chosen to simply count out the number of tan legos (T) we had at the start,
double that number, and then count of the necessary number of grey legos (G) to make the
combination TG2. That method would allow us to avoid the analytical balance altogether.
 Why do we have to measure and calculate the masses of magnesium and chlorine to combine
them in the right particle ratio? In other words, why can’t we just count out the number of
each atoms of each element needed for the chemical reaction?