Why are the elements arranged in the periodic table in their specific order?

• A. They are arranged based on the order in which they were discovered.
• B. They are arranged alphabetically by their chemical symbols.
• C. They are arranged by increasing atomic mass, regardless of their chemical properties.
• D. They are arranged by increasing atomic number, which reflects the number of protons in each element.

Answer: (D)

Verified step by step guidance

1. Understand that the periodic table is a systematic arrangement of elements based on their atomic structure.
2. Recognize that each element is defined by its atomic number, which is the number of protons in its nucleus.
3. Know that the elements are arranged in order of increasing atomic number, not by discovery date, alphabetical order, or atomic mass alone.
4. Realize that this arrangement groups elements with similar chemical properties into columns (called groups or families) because elements with the same number of valence electrons exhibit similar behavior.
5. Conclude that the periodic table's order reflects the periodic law, which states that the properties of elements repeat periodically when arranged by increasing atomic number.