Properties of Transition Metals and Coordination Chemistry

Transition Metal Atoms
- Scandium (Sc): [Ar] 4s² 3d¹
- Titanium (Ti): [Ar] 4s² 3d²
- Vanadium (V): [Ar] 4s² 3d³
- Chromium (Cr): [Ar] 4s¹ 3d⁵ notable exception
- Copper (Cu): [Ar] 4s¹ 3d¹⁰ notable exception
Transition Metal Ions
- Titanium ion (Ti³⁺): [Ar] 3d¹
- Vanadium ion (V³⁺): [Ar] 3d²
- Chromium ion (Cr³⁺): [Ar] 3d³

General Note:
- Except for Scandium (Sc) and Titanium (Ti), transition metals typically exhibit a gradual decrease in atomic radii across a period due to the increase in nuclear charge which results in greater attraction between the nucleus and the electron cloud.
Bond Types:
- Covalent Bond: shares electrons
- Ionic Bond: transfers electrons
- Coordinate Covalent Bond: involves one atom donating both electrons to the bond.
Behavior of Electrons in Transition Metals:
- Electrons in the 4s orbital are filled before the 3d orbital, with exceptions during ionization where typically 4s electrons are removed before 3d electrons.
Factors Affecting Atomic Radius:
- Shielding effect due to inner electrons causes less effective nuclear charge felt by outer electrons.
- Atoms on the left of the d-block are larger due to lower nuclear charge, while right are drawn closer due to higher nuclear charge.
- Notably, certain metals like cobalt may not follow expected trends due to these complex shielding effects.
Contraction in Atomic Radii:
- Contrast exists in the second (4d) and third series (5d) due to the presence of f-electrons which do not effectively shield nuclear charge leading to smaller atomic sizes as we progress through the series.

Definition:
- Coordination compounds are compounds containing a central metal atom or ion surrounded by one or more molecules or anions known as ligands.
Example:
- [Pt(NH)₆]Cl₄
Complex Ions (or Coordination Complexes):
- Comprised of a metal atom or ion surrounded by 2 or more ligands.
Counterions:
- These are neutral or charged ions present in the compound to balance the overall charge of the complex.

Color:
- Varies depending on the nature of ligands and their arrangement around the metal.
- Example Colors:
- Co(NH₃)₆³⁺: [Color]
- Co(NH₃)₅NCS²⁺: [Color]
- Co(NH₃)₅H₂O³⁺: [Color]
- Co(NH₃)₅Cl²⁺: [Color]
Factors Affecting Color:
- The charge and environment surrounding the central metal ion affect the absorption of light, resulting in varying colors.

Coordination Number:
- Defined as the number of ligands bound to the central metal atom.
- Typical Coordination Numbers:
- 1, 2: linear
- 4: tetrahedral
- 6: octahedral
Ligands:
- Chemical groups attached to a central metal atom or ion.
- Examples of ligands with their corresponding coordination numbers:
- 1: Agonist
- 4, 6: Tetrahedral complexes
- 2, 4, 6 or more: octahedral configurations

Types of Magnetism:
- Some complexes are diamagnetic (all paired electrons) and some are paramagnetic (1 or more unpaired electrons).
- Example: A frog levitated in a strong magnetic field demonstrates the diamagnetic properties of water due to the absence of unpaired electrons.

Name the cation first, followed by the anion.
State the central metal atom in the complex ion.
Name the ligands and ensure they end with appropriate suffixes.
Indicate the number of ligands with a prefix (mon-, di-, tri-, etc.).
Ligands are ordered alphabetically disregarding prefixes.
The name of the metal ion will end in a specific suffix if the complex is an anionic; otherwise, it reflects its oxidation state.
Roman numeral in parentheses indicates the oxidation state of the central metal atom in the coordination complex.

Definition:
- Structural isomers are compounds with the same chemical formula but different connectivity of atoms.
Isomers can be differentiated based on the ligands' positioning and charge.