Why is [Zn] not a transition metal, whereas silver is a transition element?

Which bivalent cation in 3d transition series is most paramagnetic and why?

To understand why zinc (Zn) is not classified as a transition metal while silver (Ag) is, we need to delve into the definitions and characteristics of transition metals, as well as the electronic configurations of these elements. Additionally, we will explore the paramagnetic properties of bivalent cations in the 3d transition series.

Defining Transition Metals

Transition metals are typically defined as elements that have an incomplete d subshell in one or more of their oxidation states. This characteristic allows them to exhibit unique properties such as variable oxidation states, the ability to form colored compounds, and magnetic properties.

Why Zinc is Not a Transition Metal

Zinc has the electronic configuration of [Ar] 3d¹⁰ 4s². In its common oxidation state of +2, zinc loses the two 4s electrons, resulting in a 3d¹⁰ configuration. This means that zinc has a completely filled d subshell in its most stable oxidation state, which does not meet the criteria for being a transition metal. In contrast, transition metals like iron (Fe) and copper (Cu) have partially filled d orbitals, allowing them to exhibit the properties typical of transition metals.

Silver as a Transition Element

Silver, on the other hand, has the electronic configuration of [Kr] 4d¹⁰ 5s¹. In its common oxidation state of +1, silver loses one 5s electron, resulting in a 4d¹⁰ configuration. Although the 4d subshell is filled, silver can still exhibit variable oxidation states, particularly in its +1 state, which allows it to be classified as a transition metal. The ability to form complexes and exhibit metallic bonding further supports its classification.

Paramagnetism in the 3d Transition Series

Paramagnetism arises from the presence of unpaired electrons in an atom or ion. In the 3d transition series, we can examine the bivalent cations to determine which one is the most paramagnetic.

Identifying the Most Paramagnetic Cation

Among the bivalent cations in the 3d transition series, manganese (Mn²⁺) is the most paramagnetic. Manganese has the electronic configuration of [Ar] 3d⁵ when in the +2 oxidation state. This configuration includes five unpaired electrons in the 3d subshell, which contributes to its strong paramagnetic behavior.

• Scandium (Sc²⁺): [Ar] 3d¹ (1 unpaired electron)
• Titanium (Ti²⁺): [Ar] 3d² (2 unpaired electrons)
• Vanadium (V²⁺): [Ar] 3d³ (3 unpaired electrons)
• Chromium (Cr²⁺): [Ar] 3d⁴ (4 unpaired electrons)
• Manganese (Mn²⁺): [Ar] 3d⁵ (5 unpaired electrons)
• Iron (Fe²⁺): [Ar] 3d⁶ (4 unpaired electrons)
• Cobalt (Co²⁺): [Ar] 3d⁷ (3 unpaired electrons)
• Nickel (Ni²⁺): [Ar] 3d⁸ (2 unpaired electrons)

As you can see, manganese has the highest number of unpaired electrons, making it the most paramagnetic cation in the 3d transition series. This property is significant in various applications, including magnetic materials and catalysts.

In summary, zinc is not a transition metal due to its filled d subshell in its common oxidation state, while silver qualifies as a transition element because of its ability to form variable oxidation states. Manganese, with its five unpaired electrons, stands out as the most paramagnetic bivalent cation in the 3d transition series.