Question

the periodic table is arranged in rows called periods and columns known as groups or families. for the main group elements (groups 1–2 and 13–18), elements in the same group share the same number of valence electrons. this similarity in valence electrons results in similar chemical properties among these elements.

why do elements in the same group of the periodic table often have similar chemical properties?

○ they share the same number of valence electrons.

○ they have the same number of neutrons.

○ they are found in the same period.

○ they all have metallic and nonmetallic properties.

Explanation:

To determine the answer, we analyze each option:

• Option 1: The passage states that for main group elements, those in the same group share the same number of valence electrons, and this similarity leads to similar chemical properties. This matches the explanation.
• Option 2: The number of neutrons isn't related to chemical properties based on group placement. Different isotopes of an element (same group) have different neutrons.
• Option 3: Elements in the same group are in different periods (periods are rows, groups are columns).
• Option 4: Not all elements in a group have both metallic and nonmetallic properties (e.g., Group 1 metals are all metallic).

Answer:

A. They share the same number of valence electrons.