4.1.2 The Reactivity Series

Reactivity Trends in the Periodic Table

• Down a Group: In the periodic table, as you move down a group (a vertical column), the reactivity of metals increases. This trend is especially clear in Groups 1 and 2. For example, lithium (Li) and beryllium (Be), which are at the top of their respective groups, are less reactive than francium (Fr) and radium (Ra), which are at the bottom.
• Across a Period: Moving from right to left across a period (a horizontal row) also increases metal reactivity. Metals on the left, such as sodium (Na) and potassium (K), are more reactive compared to those on the right, like platinum (Pt).

Understanding Reactivity

• Highly reactive metals lose electrons readily, making them very reactive. For example, sodium and potassium react explosively with water.
• Less reactive metals hold onto their electrons more tightly, making them less likely to react. Gold (Au), for example, does not react with water or dilute acids.

The Reactivity Series in Practice

Scientists have arranged metals in the Reactivity Series by observing their reactions with water and acids. The higher a metal is in the series, the more vigorously it reacts:

• Top of the series: Metals like potassium, sodium, and calcium react strongly with water and acids, producing hydrogen gas and a salt.
• Bottom of the series: Metals like silver, gold, and platinum show little to no reaction under the same conditions. This series also includes some non-metals, such as carbon and hydrogen, which helps determine how metals can be extracted from their ores.