In the periodic table, what does the term "family" (also called a group) refer to?

• A. A vertical column of elements that have similar chemical properties
• B. A set of elements arranged in order of decreasing atomic number
• C. A horizontal row of elements that have the same number of electron shells
• D. All elements that are gases at room temperature

Answer: (A)

Verified step by step guidance

1. Understand that the periodic table is organized in two main directions: vertically and horizontally.
2. Recognize that a 'family' or 'group' in the periodic table refers to elements arranged in a vertical column.
3. Know that elements in the same family share similar chemical properties because they have the same number of valence electrons.
4. Contrast this with a 'period,' which is a horizontal row where elements have the same number of electron shells but different properties.
5. Therefore, the term 'family' or 'group' specifically means a vertical column of elements with similar chemical behavior.