Final answer:
The Periodic Table categorizes chemical elements by atomic numbers and similar properties. Elements in the same group react similarly, while the period indicates their atomic and energy levels. Key groups include alkali metals, alkaline earth metals, transition metals, halogens, and noble gases.
Step-by-step explanation:
The Periodic Table is a comprehensive chart that organizes all known chemical elements based on their atomic numbers and chemical properties. Elements in the same column, known as groups, exhibit similar chemical behaviors, while each horizontal row, termed a period, indicates an increase in atomic and energy levels.
Group 1 elements are the alkali metals, Group 2 contains alkaline earth metals, Groups 3-12 are called transition metals, Group 17 comprises the halogens, and Group 18 consists of the noble gases. The lanthanides and actinides are two separate rows that generally fit into Group 3. Understanding these groupings and the table's structure will arm you with the ability to predict chemical reactions and the properties of elements.