Final answer:
The transition metals are elements with partially filled d subshells, which are denoted as Groups 3-12 on the periodic table. These metals often form ions by losing s electrons first, demonstrating metallic properties with varying reactivity.
Step-by-step explanation:
The transition metals are elements with partially filled d subshells. This characteristic defines the transition elements found in Groups 3-12 on the periodic table, which constitute the d-block elements. The transition metals include familiar metals such as iron, copper, and gold, and these metals are known for their ability to form ions with varying charges, primarily through the loss of their outermost s electrons before any d electrons are lost.
For instance, the electron configuration of iron is written as [Ar]3d⁵ 4s², and when it forms Fe²⁺ ion, it loses the two 4s electrons first, resulting in [Ar]3d⁶. The transition metals also exhibit typical metallic properties but are generally less reactive than metals in Groups 1 and 2.
It's important to note that although the f-block elements, which include the lanthanides and actinides, are also often mentioned in the context of transition metals due to their partially filled d orbitals before f orbitals, they are correctly classified as inner transition metals.