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The physical and chemical properties of matter are a series of characteristics that allow us to describe it and identify it. Chemical properties are those characteristics that are associated with changes in the chemical composition of substances . In other words, they are those characteristics that a chemical substance possesses by virtue of the chemical reactions in which it can participate.
This means that, unlike physical properties, chemical properties only appear and can be observed or measured when bonds are broken and/or formed, or when the valence electrons of the atoms that are part of a compound are rearranged. substance.
Importance of chemical properties
Knowing the chemical properties of a substance can be very beneficial for a variety of reasons:
It allows us to classify substances
Different chemicals can be classified according to their chemical properties. Thus, there are substances that are acidic, basic, oxidizing, reducing, explosive, and so on.
It allows us to identify unknown substances
This is because each substance has a particular set of chemical properties, so observing these properties and comparing them with their values for other known substances can help us identify a substance, or at least deduce part of its nature. structure.
They allow to separate mixtures of substances
Differences in chemical properties such as acid-base properties or reactivity towards certain reagents can be used to separate mixtures that are difficult to isolate by other means. For example, the reaction of a racemic mixture of enantiomers with an optically active salt produces a pair of diastereomeric salts that are much easier to separate than the parent enantiomers.
Reactivity is also the working principle of affinity chromatography columns and ion exchange columns.
They allow to purify individual substances
Since it allows separating chemicals from each other, chemical properties can also be used to purify chemicals, as it is the same as separating them from impurities.
Helps us identify potential uses for a substance
Many chemical properties such as flammability and heat of combustion help us know that a substance can be used as fuel. Other properties such as chemical stability or thermal stability help us to identify substances that can withstand high temperatures. The same happens with the other chemical properties. Each of them can indicate the potential use that we can give to each particular substance.
They allow predicting the behavior of substances
Scientists use chemical properties to find out if a substance will participate in a chemical reaction. This means that with them they can predict the behavior of substances against different reagents.
13 Examples of Chemical Properties
1.Oxidation state
The oxidation state of an atom refers to the number of electrons it has gained or lost after combining or bonding with another atom. Since it is a property of an element that can only be observed after a chemical reaction with another atom has occurred, it is a chemical property.
2. Electronegativity
This is a property of the elements that refers to the tendency to attract towards itself the electrons that are part of a chemical bond. For this reason, it is one of the properties that defines the type of bond that will be formed between two atoms, but said bond cannot be observed until after the reaction has taken place, so it is also a chemical property. .
3. Coordination number
This property indicates how many atoms, ions, or molecules can be attached directly to a central atom or ion through dative covalent bonds in a coordination complex.
4. Chemical stability
Chemical stability indicates whether or not a substance has little tendency to react with different chemical agents such as acids, bases, oxidants, corrosives, etc. In other words, it is a property that indicates how capable a substance is of withstanding chemical attack by other substances.
5. Reactivity with water
There are many substances that react violently with water while others do not. Reactivity with water is a chemical property that indicates this behavior. Due to the ubiquity of water almost everywhere, reactivity with water is a very important property that provides invaluable information related to the safe handling of a chemical.
6. Thermal stability
Virtually all chemicals decompose at high temperatures, but there are some that withstand much higher temperatures than others. This ability to resist a chemical change with increasing temperature is called thermal stability. This stability is measured in terms of the temperature at which a chemical change is observed, so it is a chemical property.
7. Flash or flash point
It is defined as the minimum temperature at which the vapor pressure of a volatile and flammable substance is sufficient for the combustion of the vapor-water mixture to occur, given that the ignition spark is provided.
8. Flash point
It is the minimum temperature for the combustion reaction to start spontaneously.
9. Flammability
Flammability is a property that indicates the tendency of a substance to undergo the combustion reaction when mixed with air. This property depends directly on the flash point and allows materials to be classified as flammable or combustible, depending on whether their flash point is less than or greater than 37.8°C, respectively.
10. Enthalpy of formation
This is a property that indicates the amount of heat that is released when forming one mole of a pure substance from its constituent elements in their most stable natural states, given that the reaction is carried out at constant pressure.
11. Heat of combustion
It represents the amount of heat released when one mole of a substance is completely burned at constant temperature and pressure. This property is a measure of the amount of chemical energy available in the bonds that make up a (usually organic) molecule.
12. Acid/base properties
This property indicates a chemical’s tendency to produce acidic or basic solutions, or its tendency to participate in acid/base neutralization reactions when reacted with an acid or base. Since the pH of the solution or reaction products are only observed after a chemical reaction has occurred, this represents a chemical property.
13. Toxicity
Toxicity indicates whether or not a chemical substance will have adverse effects on the health of either people or other species of living beings. This depends on the occurrence of many biochemical reactions that can affect the functioning of the different cellular functions of a living being, so it is undoubtedly a chemical property.
References
Chang, R., & Goldsby, K. (2015). Chemistry (12th ed.). New York, New York: McGraw-Hill Education.
Brown, T. (2021). Chemistry: The Central Science, 11/ed. (11th ed.). London, England: Pearson Education.
Flowers, P., Neth, EJ, Robinson, WR, Theopold, K., & Langley, R. (2019). Chemistry: Atoms First 2e . Houston, Texas: Open Stax. Retrieved from https://openstax.org/books/chemistry-atoms-first-2e/pages/1-introduction
Flowers, P., Theopold, K., Langley, R., & Robinson, WR (2019). Chemistry 2e . Houston, Texas: OpenStax Retrieved from https://openstax.org/books/chemistry-2e/pages/1-1-chemistry-in-context
