Which of the following contains a coordinate covalent bond? (Hint: How many covalent bonds would you expect the central atom (underlined/bold) to form?) a. PbCl₂ b. Cu (NH₃)₄²⁺ c. NH⁺₄

Verified step by step guidance

1. Identify the central atom in each compound: Pb in PbCl₂, Cu in Cu(NH₃)₄²⁺, and N in NH₄⁺.
2. Recall that a coordinate covalent bond (also known as a dative bond) occurs when one atom donates both electrons to form a bond.
3. Consider the typical bonding behavior of each central atom: Pb typically forms 2 bonds, Cu can form complex ions with ligands, and N typically forms 3 bonds but can form 4 in certain cases.
4. Examine Cu(NH₃)₄²⁺: Copper (Cu) is a transition metal that can form complex ions with ligands like NH₃, where NH₃ donates a lone pair to Cu, forming a coordinate covalent bond.
5. Conclude that Cu(NH₃)₄²⁺ contains a coordinate covalent bond, as NH₃ acts as a ligand donating a lone pair to the central Cu atom.

Key Concepts

Covalent Bonds

Covalent bonds are formed when two atoms share one or more pairs of electrons. This type of bond typically occurs between nonmetals and is characterized by the mutual attraction of the shared electrons to the nuclei of both atoms. Understanding the number of covalent bonds an atom can form is crucial for predicting molecular structure and reactivity.

Coordinate Covalent Bonds

A coordinate covalent bond, also known as a dative bond, occurs when one atom donates both electrons to a bond, while the other atom contributes none. This type of bond is significant in complex ions and coordination compounds, where a central atom, often a metal, is surrounded by ligands that can donate electron pairs. Identifying these bonds requires knowledge of the electron-donating capabilities of the involved species.

Central Atom and Coordination Number

The central atom in a molecule or complex is typically the atom that forms the most bonds and is often a metal in coordination chemistry. The coordination number refers to the number of bonds formed between the central atom and surrounding atoms or ligands. Understanding the expected coordination number helps in determining the type of bonds present, including whether any are coordinate covalent.