Transition metals are a group of metallic elements found in the d-block of the periodic table. They are characterized by their ability to form variable oxidation states and complex ions, making them essential in various chemical reactions. Common examples include iron, copper, and nickel, which play crucial roles in industrial processes and biological systems. These metals are known for their high melting and boiling points, as well as their ability to conduct electricity and heat. Transition metals often exhibit vibrant colors in their compounds, which is a result of d-d electron transitions. Their unique properties make them valuable in applications ranging from catalysts to electronic devices.