Question

part 1: trends in properties within groups 1) place a small strip of magnesium in a test tube and cover with water. look closely and observe what happens. record your observations in the chart. 2) place a small piece of calcium in a test tube with several milliliters of water. record your observations in the chart. 3) what might be a reason for the difference in behavior between magnesium and calcium when placed in water? (hint: lithium, sodium, and potassium are also progressively more reactive).

Explanation:

Step1: Recall periodic - table trends

Elements in the same group of the periodic table show similar chemical behavior, and reactivity with water generally increases down a group. Magnesium and calcium are in Group 2 (alkaline - earth metals).

Step2: Analyze electron - shell structure

Calcium has more electron shells than magnesium. As we move down Group 2, the outermost electrons are further from the nucleus and are more easily lost. This makes calcium more reactive with water than magnesium.

Step3: Consider ionization energy

The ionization energy (the energy required to remove an electron) decreases down Group 2. Calcium has a lower ionization energy than magnesium, so it can more readily donate electrons to water, resulting in a more vigorous reaction.

Answer:

Calcium is more reactive with water than magnesium because as we move down Group 2 of the periodic table, the number of electron shells increases, the outermost electrons are further from the nucleus, and the ionization energy decreases. This makes it easier for calcium to lose its outermost electrons and react with water compared to magnesium.