Question

How does the reactivity of a nucleophile change across a row in the periodic table?

Answer 1

In order to know about the reactivity of a nucleophile across a row in the periodic table, we must know that about the nucleophile. The name nucleophile indicates ‘nucleus loving species’. To determine the strength of a nucleophile, we will consider the nucleophilicity.

Complete answer:
Nucleophile means ‘nucleus loving species’. It describes the tendency of an electron rich species to get attracted with the positive nuclear charge of an electron deficient species. To determine a good nucleophile, we will consider its nucleophilicity which indicates the strength of a nucleophile. The nucleophilicity expresses the ability of the nucleophile to react. If more electrons are available, the system will be more nucleophilic.
According to the question, we have to determine the reactivity of a nucleophile change across a row in the periodic table. As we know that, electronegativity increases across the row i.e. when we go from left to right in the periodic table. It indicates that the atoms on the right hand side of the periodic table are less likely to donate their electrons to form bonds with other atoms. Therefore, nucleophilicity decreases from left to right in the periodic table.
Hence, we can say that reactivity of a nucleophile decreases from left to right in a row across the periodic table.

Note:
Always remember that nucleophiles can be neutral or negatively charged species. It is very important to note that nucleophiles are a good Lewis base i.e. it can donate electrons. Also, the relative strength of the nucleophile i.e. nucleophilicity depends on several factors including charge, basicity, solvent, polarizability and nature of the substituents.