Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

According to the Law of Chemical Periodicity, what are the properties of elements functions of?

1. Atomic symbols

2. Mass and volume

3. Atomic number

4. Electron configuration

The correct answer is: Atomic number

The correct choice is based on the understanding that the properties of elements are periodic functions of their atomic number. The Law of Chemical Periodicity, first articulated by Dmitri Mendeleev and later refined, asserts that when elements are arranged in order of increasing atomic number, there is a recurring pattern in their chemical properties. This periodic table arrangement highlights trends in characteristics such as reactivity, ionization energy, electronegativity, and atomic size. While atomic symbols, mass, volume, and electron configuration indeed play roles in understanding elements, the foundational principle of periodicity specifically ties to atomic number. The atomic number uniquely identifies an element and determines the number of protons in an atom's nucleus. This proton count is crucial because it influences how an atom interacts chemically with others, thus dictating its properties. Electron configuration, although it closely relates to the behavior of electrons and chemical bonding, derives from the atomic number and is an expression of how those electrons are arranged in an atom.