How many unpaired electrons are present in \(\mathrm{Ni}^{2+}\) ? (a) 8 (b) 4 (c) 2 (d) 0

Understanding electron configuration is crucial when trying to determine properties like magnetism and chemical reactivity. Electron configuration refers to the distribution of electrons in an atom or ion amongst the various orbitals within atoms. Each element has a unique electron configuration that describes where the electrons are located.

Atoms are structured in shells and subshells. The first two electrons of an atom fill the lowest energy level, the 1s orbital. As we move to higher elements, more subshells come into play, including s, p, d, and f. The notation, such as 3d^8 4s^2 used for Nickel, tells us the electron occupies the 3rd shell 'd' subshell with eight electrons and the 4th shell 's' subshell with two electrons.

Learning to write and interpret electron configurations is essential for predicting the chemical, optical, and magnetic behavior of elements.

Transition metals occupy the central block of the periodic table and have electron configurations that display a wide range of possible oxidation states due to the near energy levels of their s and d orbitals. These metals, including nickel, iron, and copper, have valence electrons in two shells instead of just one, which leads to their unique chemistry and metallic properties, such as high melting points, colorful compounds, and, often, magnetic properties.

Transition metals can use the d-subshell electrons to form bonds, a property that is vital in many industrial catalysts and in the biological function of essential metalloproteins in many organisms. They can lose electrons from their s orbital, or their d orbital, or both during reactions, which provides them with a rich chemistry.

Creating a Nickel Ion

The electron configuration for the Nickel ion (Ni^2+) is different from that of the neutral Nickel atom due to the loss of two electrons. When a Nickel atom undergoes ionization to form Ni^2+, it loses the two electrons from its 4s orbital, leading to the configuration [Ar]3d^8, which is associated with the exercise originally listed.

Ionization changes how an element interacts with its surroundings by altering its electrical charge and changes how it bonds with other atoms or ions. Nickel ions play a significant role in various metabolic processes and are widely used in plating and alloys.

Paramagnetism is a type of magnetism that occurs in materials with unpaired electrons that are attracted to magnetic fields. The more unpaired electrons an ion or an atom has, the stronger its paramagnetic effects will be.

In the context of the provided exercise, knowing the electron configuration of Ni^2+ allows us to determine the number of unpaired electrons. Since the electronic arrangement in the 3d subshell for [Ar]3d^8 would have two unpaired electrons, Ni^2+ exhibits paramagnetism. This property is utilized in many technological applications such as MRI machines, where paramagnetic compounds are used as contrast agents to enhance the quality of the images.