Question

Similarity in chemical properties of the atoms of elements in a group of the Periodic table is most closely related to :

• A. atomic numbers
• B. atomic masses
• C. number of principal energy levels
• D. number of valence electrons

Answer 1

The Correct Option is A

The question asks about the factor that is most closely related to the similarity in chemical properties of elements in a group of the Periodic table. Let's examine each option to understand which one primarily accounts for these similarities:

1. Atomic Numbers:
   • The atomic number of an element is defined as the number of protons in the nucleus of its atoms.
   • While the elements in a group of the Periodic Table have different atomic numbers, this feature does not directly correspond to similarities in their chemical properties.
2. Atomic Masses:
   • Atomic mass is the average mass of atoms of an element, calculated using the relative abundance of isotopes.
   • Although atomic masses generally increase as you move down a group, they do not determine chemical properties.
3. Number of Principal Energy Levels:
   • This refers to the number of electron shells or orbits around the nucleus.
   • Elements in the same group have different numbers of principal energy levels, and it primarily affects the size but not the chemical properties directly.
4. Number of Valence Electrons:
   • This is the key factor for determining chemical properties.
   • Elements in the same group have the same number of valence electrons, which directly affects their chemical properties, such as reactivity and bonding characteristics.

Therefore, the correct answer is: number of valence electrons.

Understanding this concept is crucial because elements with the same number of valence electrons exhibit similar chemical behavior. This principle is foundational to predicting reactions and bonding in chemistry.