How many electrons does the nickel atom lose when forming nickel(II) nitrate? When forming nickel(II) sulfate?

Understanding the valency of metals is crucial when unraveling their chemical behavior, particularly in the formation of compounds. Valency, in simple terms, is the ability of an atom to combine with other atoms, and is determined by the number of electrons an atom can lose, gain, or share. Metals, found on the left side of the periodic table, typically have a positive valency, as they tend to lose electrons to achieve a stable electronic configuration.

For instance, in transition metals like nickel, valency can vary due to their ability to lose different numbers of electrons present in the d-orbitals. The Roman numerals that we often see in the names of metal compounds, such as nickel(II) nitrate, represent the valency of the metal cation. In this example, the numeral (II) indicates that nickel has a valency of +2, meaning it loses two electrons to other atoms or molecules during chemical reactions to form compounds.

The formation of ionic compounds is a fundamental concept in chemistry involving the transfer of electrons between atoms to achieve stable electron configurations. These compounds are typically formed between metals, which are electron donors, and nonmetals, which are electron acceptors. An ionic bond is the electrostatic force that holds these charged particles together.

Metal atoms, when interacting with nonmetal atoms, will lose their valence electrons to form positively charged ions, known as cations. The nonmetals, on the other hand, will gain those electrons to become negatively charged ions, called anions. This exchange leads to the formation of a crystalline lattice structure where each ion is surrounded by ions of opposite charge, optimizing electrostatic attraction and hence the overall stability of the compound.

In the case of nickel(II) nitrate or sulfate, nickel atom loses two electrons to form the Ni²⁺ ion, which combines with the nitrate (NO₃⁻) or sulfate (SO₄²⁻) anions, respectively, to produce the corresponding ionic compounds.

Nickel, being a transition metal, exhibits multiple oxidation states, which is a term used to describe the charge of an ion after it has lost or gained electrons during a reaction. For nickel, common oxidation states are +2 and +3, although it can exhibit other less stable states.

The +2 oxidation state is the most stable and common for nickel in its compounds, such as in nickel(II) nitrate and nickel(II) sulfate. This is indicated by the numeral (II) in the name of the compound. As explained in the textbook solution, to achieve this oxidation state, a nickel atom loses two electrons. This electron loss leads to a positive charge on the nickel, symbolized as Ni²⁺. The knowledge of oxidation states is not only key to understanding the type of chemical bonds formed but also crucial in redox reactions, naming of chemical compounds, and in determining the color and magnetic properties of substances.