What shows the repeating pattern of element properties in a chart?

• A. Cross-table
• B. Noble-gas chart
• C. Periodic table
• D. Element list

Answer: (C)

The repeating pattern of element properties is shown by the periodic table. Elements are arranged by increasing atomic number in rows and columns so that those with the same number of valence electrons line up in the same vertical groups. This arrangement makes similar chemical behavior emerge among elements in the same group, since they share similar electron configurations and bonding tendencies. As you move across a period, properties change gradually, and as you move down a group, trends become more pronounced. This repeating pattern, called periodicity, lets you predict how an element will behave based on where it sits on the chart. For example, elements in the alkali-metal family are highly reactive and form +1 ions, while the noble gases are very unreactive because their outer shells are full. Other formats might show some relationships, but they don’t reveal the overall repeating trend across many elements as clearly as the periodic table.