Chemical reactivity in d-block elements refers to how these elements, also known as transition metals, react with other substances. The reactivity of these elements is generally less than that of the s-block elements, but more than the p-block elements. This is due to the presence of incompletely filled d-orbitals.

The reactivity of d-block elements can be influenced by several factors:

1. Atomic Size: As we move from left to right in the periodic table, the atomic size decreases. This is due to an increase in nuclear charge which pulls the electrons closer to the nucleus, thus decreasing the atomic size. Smaller atoms are generally more reactive because they can more easily gain or lose electrons.

2. Ionization Energy: This is the energy required to remove an electron from an atom. D-block elements have relatively high ionization energies due to the presence of more protons in the nucleus, which makes them less likely to lose electrons and therefore less reactive.

3. Oxidation State: D-block elements can exist in a variety of oxidation states due to the presence of incompletely filled d-orbitals. This can affect their reactivity. For example, elements in a higher oxidation state are generally more reactive.

E values in chemistry refer to electrode potentials. The standard electrode potential (E°) is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. Each species has its own intrinsic standard electrode potential; a more positive value indicates a greater tendency to be reduced.

The E° values of d-block elements are generally less positive than those of s-block elements, but more positive than those of p-block elements. This is because d-block elements have a moderate ability to gain or lose electrons, which is reflected in their intermediate E° values.

In the context of NCERT Class 12 Chemistry, these concepts are important for understanding the properties and behaviors of d-block elements, and for predicting the outcomes of chemical reactions involving these elements.

Question

Chemical reactivity in d-block elements refers to how these elements, also known as transition metals, react with other substances. The reactivity of these elements is generally less than that of the s-block elements, but more than the p-block elements. This is due to the presence of incompletely filled d-orbitals.

The reactivity of d-block elements can be influenced by several factors:

1. Atomic Size: As we move from left to right in the periodic table, the atomic size decreases. This is due to an increase in nuclear charge which pulls the electrons closer to the nucleus, thus decreasing the atomic size. Smaller atoms are generally more reactive because they can more easily gain or lose electrons.

2. Ionization Energy: This is the energy required to remove an electron from an atom. D-block elements have relatively high ionization energies due to the presence of more protons in the nucleus, which makes them less likely to lose electrons and therefore less reactive.

3. Oxidation State: D-block elements can exist in a variety of oxidation states due to the presence of incompletely filled d-orbitals. This can affect their reactivity. For example, elements in a higher oxidation state are generally more reactive.

E values in chemistry refer to electrode potentials. The standard electrode potential (E°) is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. Each species has its own intrinsic standard electrode potential; a more positive value indicates a greater tendency to be reduced.

The E° values of d-block elements are generally less positive than those of s-block elements, but more positive than those of p-block elements. This is because d-block elements have a moderate ability to gain or lose electrons, which is reflected in their intermediate E° values.

In the context of NCERT Class 12 Chemistry, these concepts are important for understanding the properties and behaviors of d-block elements, and for predicting the outcomes of chemical reactions involving these elements.

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