(a) Why is calcium generally more reactive than beryllium? (b) Why is calcium generally less reactive than rubidium?

Verified step by step guidance

Step 1: Understand the position of calcium, beryllium, and rubidium in the periodic table. Calcium (Ca) is in Group 2 (alkaline earth metals), beryllium (Be) is also in Group 2, and rubidium (Rb) is in Group 1 (alkali metals).

Step 2: Discuss the reactivity trend in Group 2. Reactivity increases down the group as the atomic size increases, making it easier for the atom to lose its outer electrons. Calcium is below beryllium in Group 2, hence more reactive.

Step 3: Explain the concept of ionization energy. Ionization energy is the energy required to remove an electron from an atom. Lower ionization energy means higher reactivity. Calcium has a lower ionization energy than beryllium, making it more reactive.

Step 4: Compare the reactivity of Group 1 and Group 2 elements. Group 1 elements (alkali metals) are generally more reactive than Group 2 elements because they have only one electron to lose, which requires less energy.

Step 5: Analyze the reactivity of calcium and rubidium. Rubidium, being in Group 1, has a lower ionization energy than calcium, making it easier to lose its single valence electron, thus more reactive than calcium.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Reactivity of Metals

The reactivity of metals is influenced by their atomic structure, particularly the number of valence electrons and their ability to lose these electrons. Metals with fewer valence electrons tend to be more reactive because they can easily lose these electrons to form positive ions. This trend is observed in the periodic table, where reactivity generally increases down a group.

Group Trends in the Periodic Table

In the periodic table, elements are arranged in groups that share similar properties. As you move down a group, such as from beryllium to calcium, the atomic size increases, and the outer electrons are further from the nucleus. This increased distance reduces the effective nuclear charge felt by the valence electrons, making it easier for these electrons to be lost, thus increasing reactivity.

Comparison of Alkali and Alkaline Earth Metals

Alkali metals, like rubidium, are generally more reactive than alkaline earth metals, such as calcium, due to their single valence electron. Alkali metals can lose this electron very easily, leading to high reactivity. In contrast, alkaline earth metals have two valence electrons, which makes them less reactive than alkali metals but more reactive than transition metals, as they require more energy to lose both electrons.

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