Why do elements in the same group of the periodic table typically have similar chemical properties?

• A. They have identical atomic masses.
• B. They have the same number of valence electrons.
• C. They are all metals.
• D. They have the same atomic number.

Answer: (B)

Verified step by step guidance

1. Understand that elements in the same group (vertical column) of the periodic table have similar chemical properties because chemical behavior is largely determined by the number of valence electrons, which are the electrons in the outermost shell of an atom.
2. Recall that elements in the same group have the same number of valence electrons, which means they tend to form similar types of bonds and have similar reactivity patterns.
3. Recognize that atomic mass and atomic number increase as you move down a group, so these are not the reasons for similar chemical properties within a group.
4. Note that being metals or nonmetals is not a defining factor for similarity within a group, as groups can contain different types of elements (e.g., metals and nonmetals).
5. Conclude that the key reason for similar chemical properties in elements of the same group is their identical number of valence electrons, which governs their chemical bonding and reactions.