Coordination Compounds

Step 1: Colour of Ni .
The color of Ni ions in aqueous solution is green. This is due to the electronic transitions in the -orbitals of the Ni ion.

Step 2: Conclusion.
The color of Ni is green.

Step 1: Understanding EDTA.
EDTA stands for ethylenediaminetetraacetic acid, a chelating agent that binds metal ions. Its chemical formula is .

Step 2: Conclusion.
The chemical name of EDTA is Ethylenediaminetetraacetic acid.

Step 1: Define oxidation number.
The oxidation number (or oxidation state) of an atom in a molecule or ion represents the number of electrons that the atom can donate or accept when forming a bond. In coordination compounds, the oxidation number of the central metal atom is determined by considering the charges of the ligands and the overall charge of the complex.

Step 2: Example.
In the complex , the cyanide ligand has a charge of -1. Since there are six cyanide ions, the total charge contributed by the ligands is -6. For the overall complex to have a charge of -4, the oxidation state of iron (Fe) must be +2. Thus, the oxidation number of the central metal atom (Fe) is +2.

Step 3: Conclusion.
The oxidation number of the central metal atom is the charge it has in a given complex.

Step 1: Coordination Number Definition.
The coordination number of a metal atom or ion in a coordination compound is the number of ligands directly bonded to it. It indicates the number of coordination bonds formed between the metal ion and the surrounding ligands.

Step 2: Example.
In the complex , the coordination number of the central metal ion is 6 because it is surrounded by six ammonia molecules , which are the ligands.

Step 3: Conclusion.
Thus, the coordination number is an important feature in coordination compounds and is determined by the number of ligands attached to the central metal atom.

Step 1: Hydrate Isomerism Definition.
Hydrate isomerism occurs when two or more isomers exist for a coordination compound due to the different ways in which water molecules can be incorporated into the complex. Hydrate isomers differ by the number of water molecules directly bonded to the metal ion versus those that are present in the crystal lattice.

Step 2: Example.
An example is the complex and . In the first complex, four water molecules are directly coordinated to the cobalt ion, while in the second, six water molecules are coordinated, and two chloride ions are in the crystal lattice.

Step 3: Conclusion.
Hydrate isomerism is a type of isomerism where water molecules are arranged differently within the complex, resulting in different compounds with distinct properties.

Step 1: Identify the ligands. The ligand in this compound is cyanide , which is a monodentate ligand.

Step 2: Identify the oxidation state of the metal. Nickel (Ni) in this compound is in the +2 oxidation state, because the four cyanide ions each carry a -1 charge, and the overall charge of the complex is 0. Thus, the charge on Ni must be +2.

Step 3: Write the IUPAC name. The IUPAC name is: Tetrachloronickel(II).

Step 1: Identify the ligands. The ligand in this compound is ammonia , which is a neutral ligand.

Step 2: Identify the oxidation state of the metal. Cobalt (Co) in this compound is in the +3 oxidation state, because the three chloride ions each carry a -1 charge, and the six ammonia molecules are neutral. Thus, the total charge on the complex is +3.

Step 3: Write the IUPAC name. The IUPAC name is: Hexaamminecobalt(III) chloride.