Question

question 5. rank the following elements in order of increasing reactivity. magnesium (mg), cesium (cs), calcium (ca), aluminum (al) answer: magnesium (mg) cesium (cs) calcium (ca) aluminum (al)

Explanation:

Step1: Recall reactivity trends

For metals, reactivity generally increases down a group (due to increased atomic size, easier electron loss) and decreases across a period (due to increased nuclear charge, harder electron loss).

• Aluminum (Al) is in period 3, group 13.
• Magnesium (Mg) is in period 3, group 2.
• Calcium (Ca) is in period 4, group 2.
• Cesium (Cs) is in period 6, group 1.

Step2: Compare reactivities

• Group 1 metals (like Cs) are more reactive than group 2 metals.
• Down group 2: Ca (period 4) is more reactive than Mg (period 3).
• Across period 3: Mg (group 2) is more reactive than Al (group 13).
• So the order from least to most reactive is: Al < Mg < Ca < Cs.

Answer:

Aluminum (Al) < Magnesium (Mg) < Calcium (Ca) < Cesium (Cs)