Table of Contents
Reactivity is a measure of how easily a material conducts a chemical reaction in chemistry. The reaction might include the chemical alone or in combination with other atoms or molecules, and it is usually followed by the release of energy. The most reactive elements and compounds have the potential to spontaneously or explosively ignite. They often burn in both water and oxygen in the air. The temperature has an effect on reactivity. Temperature increases the amount of energy available for a chemical reaction, making it more likely. Reactivity may also be defined as the scientific study of chemical processes and their kinetics.
Reactivity Trend in the Periodic Table
The periodic table’s arrangement of elements allows for reactivity predictions. Highly electropositive and highly electronegative materials both have a great proclivity to react. These elements are found in the periodic table’s top right and lower left corners, as well as in certain element groups. Halogens, alkali metals, and alkaline earth metals are all extremely reactive.
Fluorine, the first element in the halogen group, is the most reactive.
The most reactive metal is francium, which is also the final alkali metal (and the most expensive element). However, francium is a radioactive element that is only present in tiny levels. Cesium, which lies right above francium on the periodic table, is the most reactive metal with a stable isotope.
Noble gases are the least reactive elements. Helium is the least reactive element in this group, creating no stable compounds. Metals can exist in various oxidation states and have intermediate reactivity. Noble metals are metals with little reactivity.
Platinum is the least reactive metal, followed by gold. These metals do not dissolve easily in strong acids due to their poor reactivity. To dissolve platinum and gold, aqua regia, a combination of nitric acid and hydrochloric acid, is employed.
How Does Reactivity Work?
When the products of a chemical reaction have lower energy (greater stability) than the reactants, the material reacts. Valence bond theory, atomic orbital theory, and molecular orbital theory may all be used to forecast the energy difference. Essentially, it comes down to electron stability in their orbitals. Unpaired electrons with no electrons in similar orbitals are the most likely to interact with orbitals from other atoms, resulting in the formation of chemical bonds. Unpaired electrons with half-filled degenerate orbitals are more stable yet still reactive. Atoms having a full set of orbitals are the least reactive (octet).
The stability of electrons in atoms influences not just an atom’s reactivity, but also its valence and the sort of chemical bonds that may be formed. Carbon, for example, has a valence of 4 and normally forms 4 bonds because its ground state valence electron configuration is half-filled at 2s2 2p2. Reactivity can be explained simply as increasing with the ease of absorbing or giving an electron. In the instance of carbon, an atom can take four electrons to fill its orbital or (less frequently) contribute four outside electrons. Despite the fact that the model is based on atomic behaviour, the same idea applies to ions and molecules.
The term reactivity is frequently used to indicate the pace of a chemical reaction or how rapidly a substance will respond. The rate law relates the possibility of reacting and the pace of the reaction under this definition: Rate = K [A]
Where the rate is the change in molar concentration per second at the rate-determining phase of the reaction, k is the concentration-independent reaction constant, and [A] is the product of the molar concentrations of the reactants raised to the reaction order (which is one, in the basic equation). The equation states that the stronger the reactivity of the substance, the higher its value for k and rate.
Reactivity Series
The metal reactivity series, also known as the activity series, is the organization of metals in declining order of reactivity. The reactivity series data may be used to forecast whether one metal can displace another in a single displacement reaction. It may also be used to determine the reactivity of metals to water and acids.
Important Characteristics
- The metals near the top of the reactivity range are potent reducing agents because they are quickly oxidized, These metals discolour and corrode quickly.
- The metals’ reducing capacity weakens as they progress down the series.
- The electro-positive of the elements decreases as one moves down the metal reactivity series.
- Metals higher on the reactivity series have the capacity to displace metals lower on the reactivity series from their salt solutions.
- Another essential property of the reactivity series is that the metals’ capacity to donate electrons decreases as they move down the series.
Important Use of Reactivity Series
The reactivity series has numerous key applications aside from offering insight into the characteristics and reactivities of metals. The activity series, for example, may be used to predict the outcomes of reactions between metals and water, metals and acids, and single displacement processes between metals.
Reaction Between Metals and Water
Calcium and the metals in the reactivity series that are more reactive than calcium may react with cold water to generate the equivalent hydroxide while freeing hydrogen gas. The reaction between potassium and water, for example, produces potassium hydroxide and H2 gas, as represented by the chemical equation below.
2K + 2H2O → 2KOH + H2
Reaction Between Metals and Acids
When lead and the metals above it in the activity series react with hydrochloric or sulphuric acid, they generate salts. These reactions also result in the release of hydrogen gas. An example of such a reaction is the reaction between zinc and sulfuric acid. As byproducts, zinc sulfate and H2 gas are generated. The chemical formula is:
Zn + H2SO4 → ZnSO4 + H2
Single Displacement Reactions Between Metals
On the reactivity series, low-ranking metal ions are easily reduced by high-ranking metals. As a result, in single displacement reactions between them, low-ranking metals are easily displaced by high-ranking metals.
The displacement of copper from copper sulfate by zinc is an excellent example of such a process. This reaction’s chemical equation is as follows:
Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)
FAQ’s
What does a reactivity series reveal?
Metals are shown in descending order of reactivity in the reactivity series. The reactivity of metal can be determined by observing its responses to competition and displacement.
What is the least reactive metal?
Transition metals are elements in the periodic table that are significantly less reactive, and metals such as gold and platinum are at the bottom of the list, demonstrating nothing in the way of chemical reactivity with any typical reagents.
