Question

what are the horizontal (from left to right) parts of the periodic table called? a rows b periods c families the vertical (top to bottom) parts of the periodic table are called \groups\ or ____.

Explanation:

For the first question: The horizontal left-to-right segments of the periodic table are defined as periods; while "rows" is a common description, the formal scientific term is periods. For the second question: Vertical top-to-bottom segments are called groups, and they are also referred to as families.

Answer:

1. B. periods
2. B. families