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Counting chemical
concepts (dismissing the mole concept)
Alfredo Tifi
Istituto Tecnico Tecnologico “E. Divini”,
San Severino Marche, ITALY
ICCE – ECRICE Rome, July 19° 2012
what seems to be “logical” is really the product
of pieces of socially validated
utterances, experiences and sensory-motor
imagery.
Are the moles as simple as
the apples in a kilogram?
counting
from sequencing words to evaluating sizes
Ordered-number signs
(ORDINAL NUMBERS)
Amount-number signs
(CARDINAL NUMBERS)
spontaneous-everyday concepts are
very different from scientific concepts
Are the moles as simple as
the apples in a kilogram?The answer is NO if you want relate
understanding of MOLE to other scientific
concepts as molar mass, Avogadro's
constant, atomic mass unit, actual and
relative atom mass and number.
The response is YES if you settle for
spontaneous use of the concept of
Relative Number of Atoms (Units)
Objective
to prepare the spontaneous machinery
to calculate numerical amounts of
atoms or other units at the atomic
level, without (or before) introducing
the mole concept.
2nd GRADE 4th GRADE
number of objects
Number, measure of weight
Mole as system of scientific concepts
Avogadro's
Number
MOLE
MOLAR
MASS
Atomic
Weight
AMU
total
number
+ Carbon-12
+ Total mass
+ Amount of Substance
+ number of moles
+ atomic weight in grams
The mole is simply
the amount of
substance of a system
which contains as
many elementary
entities as there are
atoms in 0.012
kilogram of carbon 12
Relative number of unities as a
spontaneous concept
1st Gr. Secondary school
relativenumberof atoms
total mass of atoms
relative atomic mass=
Stoichiometric basic calculus
Mass of
substance A
Mass of
substance B?
Relative
Number of
A unitsor multiple
Relative
Number of
B units
Applying the spontaneous concept of
RELATIVE NUMBER OF ATOMS
RESULTS
• All students in the class mastered this simple
calculations. The relative number of atoms-
formulas-molecules-ions was really
internalized as a cardinal number of
objects, and this was completely different
from the variable “moles” that is almost never
taken as a measure of numerical amount of
substance, notwithstanding our efforts to
vehicle it from the correct academic
definition.
“Scientific/academic concepts can arise
in the child’s head only on the
foundation provided by the lower and
more elementary forms of
generalization which previously
existed.”
Lev. S. Vygotsky (1987, p.177)
L. S. Vygotsky, 1987 The Collected Works of L. S.Vygotsky, Vol I. Problems of general psychology, R.
W.Rieber and A. S. Carton (Eds.). New York: International Publishers.
CONCLUSIONS
THANK YOU FOR YOUR
ATTENTION
• Alfredo Tifi,
• ITT “E.Divini” San Severino Marche, ITALY
