AFOQT Practice Test

What does the periodic table classify elements by?

1. Only atomic weight

2. Physical and chemical properties

3. Electron configurations

4. Molecular structure

The correct answer is: Physical and chemical properties

The periodic table classifies elements primarily based on their physical and chemical properties, which include characteristics like reactivity, state at room temperature, and atomic structure. This classification allows us to see trends and patterns, such as how elements in the same group share similar traits. This organization reflects both the similarities in their physical characteristics and their behavior in chemical reactions, making it a vital tool in chemistry for predicting how different elements will interact. While the options related to atomic weight, electron configurations, and molecular structure pertain to aspects of elements, they do not encompass the overall classification system of the periodic table. Atomic weight is a consideration within the table, but it is not the sole basis for organization. Electron configurations do contribute to understanding the chemical properties of elements, yet the direct classification relies more broadly on observable properties. Molecular structure pertains to compounds formed by elements, which is outside the scope of the periodic table's classification of standalone elements.