CHEMICAL DIVISIBILITY: CONCEPTS AND EXAMPLES - CHEMISTRY - 2025

We can define divisibility in chemistry as a property of matter that allows it to separate into smaller portions. To understand the concept we can give an example.

If we take a loaf of bread and cut it in half over and over again, will we ever get to a fundamental block of matter that cannot be divided further? This question has been on the minds of scientists and philosophers for thousands of years.

Origin and concept of chemical divisibility

For a long time it was debated whether matter was made up of particles (what we know today as atoms), however, the general idea was that matter was a continuum that could be divided.

This general concept made brilliant scientists like James Clerk Maxwell (of Maxwell's equations) and Ludwing Boltzman (of Boltzman distribution) the victim of ridicule, which drove the former to madness and the latter to suicide.

In the 5th century BC, the Greek philosopher Leucippus and his disciple Democritus used the word atoms to designate the smallest individual piece of matter and proposed that the world consists of nothing more than atoms in motion.

This early atomic theory differed from later versions in that it included the idea of ​​a human soul composed of a more refined type of atom distributed throughout the body.

Atomic theory fell into decline in the Middle Ages, but was revived at the beginning of the Scientific Revolution in the 17th century.

Isaac Newton, for example, believed that matter consisted of "solid, massive, hard, impenetrable, and mobile particles."

The divisibility can occur by different methods, the most common is the divisibility by physical methods, for example chopping an apple with a knife.

However, divisibility can also occur by chemical methods where matter would be separated into molecules or atoms.

10 examples of chemical divisibility

1- Dissolve salt in water

When a salt, for example sodium chloride, is dissolved in water, a solvation phenomenon occurs where the ionic bonds of the salt are broken:

NaCl → Na ⁺ + Cl ^-

By dissolving just one grain of salt in water, it will separate into billions of sodium and chloride ions in solution.

Figure 1: dissolution of a salt in water.

2- Oxidation of metals in an acid medium

All metals, for example magnesium or zinc, react with acids, for example dilute hydrochloric acid to give hydrogen bubbles and a colorless solution of the metal chloride.

Mg + HCl → Mg ²⁺ + Cl ^- + H ₂

The acid oxidizes the metal, separating the metallic bonds to obtain ions in solution (BBC, 2014).

3- Hydrolysis of esters

Hydrolysis is the breaking of a chemical bond through water. An example of hydrolysis is the hydrolysis of esters where these are divided into two molecules, an alcohol and a carboxylic acid.

Figure 2: hydrolysis of methyl acetate.

4- Elimination reactions

An elimination reaction does exactly what it says: it removes atoms from a molecule. This is done to create a carbon-carbon double bond. This can be done using a base or an acid.

It can occur in a single concerted step (the abstraction of the proton in Cα occurring at the same time as the cleavage of the Cβ-X bond), or in two steps (cleavage of the Cβ-X bond occurs first to form an intermediate carbocation, which is then "turned off" by the abstraction of the proton in alpha-carbon).

Figure 3: elimination reactions.

5- Enzymatic reaction of aldolase

In the preparative phase of glycolysis, one glucose molecule is split into two glyceraldehyde 3-phosphate (G3P) molecules using 2 ATP.

The enzyme in charge of this incision is aldolase, which through reverse condensation divides in two the fructose 1,6-bisphosphate molecule in a G3P molecule and a dihydroxyacetone phosphate molecule that later isomerized to form another molecule of G3P.

Figure 4: Aldolase reaction.

6- Degradation of biomolecules

Not only glycolysis, but all the degradation of biomolecules in catabolism reactions are examples of chemical divisibility.

This is because they start from large molecules such as carbohydrates, fatty acids and proteins to produce smaller molecules such as acetyl CoA that enters the Krebs cycle to produce energy in the form of ATP.

7- Combustion reactions

This is another example of chemical divisibility since complex molecules such as propane or butane react with oxygen to produce CO ₂ and water:

C ₃ H ₈ + 5O ₂ → 3CO ₂ + 4H ₂ O

The degradation of biomolecules could be said to be a combustion reaction since the final products are CO ₂ and water, however these occur in many steps with different intermediaries.

8- Centrifugation of blood

The separation of the various components of blood is an example of divisibility. Despite being a physical process, the example seems interesting to me since the components are separated by difference in density by centrifugation.

The densest components, the serum with the red blood cells, will remain at the bottom of the centrifuge tube while the less dense components, the plasma, will remain at the top.

9- Bicarbonate buffer

Sodium bicarbonate, HCO ₃ ^- is the main way of transporting CO ₂ in the body as a result of metabolic degradation reactions.

This compound reacts with a proton in the medium to produce carbonic acid which is subsequently divided into CO2 and water:

HCO ₃ ^- + H ⁺ DH ₂ CO ₃ D CO ₂ + H ₂ O

Since the reactions are reversible, this is a way that the organism has, through respiration, to control the physiological pH to avoid processes of alkalosis or acidosis.

10- Division of the atom or nuclear fission

In the event that a massive nucleus (such as uranium-235) breaks down (fissions), it will result in a net energy yield. This is because the sum of the masses of the fragments will be less than the mass of the uranium core.

In the event that the mass of the fragments is equal to or greater than that of iron at the peak of the binding energy curve, the nuclear particles will be more closely bound than in the uranium nucleus and this decrease in mass occurs in energy form according to Einstein's equation.

Figure 5: fission of uranium 235.

For elements lighter than iron, fusion will produce energy. This concept led to the creation of the atomic bomb and nuclear power.

References

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