Question

1. what is a group (family)?

mark all that apply
vertical columns
horizontal rows
tells main energy level
tells the number of valence electrons if a main group element

Explanation:

• In the periodic table, a group (family) is defined as vertical columns. Horizontal rows are periods. The period number tells the main energy level of an element. For main group elements, the group number tells the number of valence electrons. So we analyze each option:
• "Vertical columns": Correct, as groups are vertical columns in the periodic table.
• "Horizontal rows": Incorrect, horizontal rows are periods, not groups.
• "Tells main energy level": Incorrect, the period number tells the main energy level, not the group.
• "Tells the number of valence electrons if a main group element": Correct, for main group elements (groups 1, 2, 13 - 18), the group number corresponds to the number of valence electrons.

Answer:

A. Vertical columns
D. Tells the number of valence electrons if a main group element