Question

Which of the following elements acts as the best reducing agent? (a) \(\mathrm{Na}\) (b) \(\mathrm{Cl}\) (c) \(\mathrm{Mg}\) (d) \(\mathrm{F}\)

Short answer

Answer: (a) Na (Sodium)

Step-by-step solution

Determine the electron loss tendencies

We need to look at the periodic table and see where these elements are placed. This way, we can get an idea of their willingness to lose or gain electrons and act as reducing agents. The elements are as follows: (a) Na (Sodium) - Group 1, Alkali metal (b) Cl (Chlorine) - Group 17, Halogen (c) Mg (Magnesium) - Group 2, Alkaline Earth metal (d) F (Fluorine) - Group 17, Halogen

Identify the characteristics of the groups

In general, elements in Group 1 and Group 2 have a greater tendency to lose electrons compared to other groups due to their low ionization energies, making them good reducing agents. On the other hand, elements from Group 17 have high electron affinity and gain electrons easily, making them poor reducing agents.

Compare elements within the same group

Since Na and Mg belong to Group 1 and Group 2 respectively, we now need to compare their electron loss tendencies. In general, elements in Group 1 have a higher tendency to lose electrons (greater reducing ability) compared to Group 2 elements.

Determine the best reducing agent

Based on the comparison of elements and their electron loss tendencies from their respective groups, we can infer that \(\mathrm{Na}\) (Sodium) from Group 1 has the highest tendency to lose electrons and hence, acts as the best reducing agent among the given elements. So, the correct answer is (a) \(\mathrm{Na}\).

Key concepts

Periodic Table

The periodic table is an organized arrangement of all known chemical elements. It is incredibly useful for chemists because it provides a lot of information about the elements and their relationships with one another.

Elements are organized in order of increasing atomic number, which is the number of protons in an atom's nucleus. Each element has a specific symbol, atomic mass, and belongs to a group or family.

• Groups: Vertical columns in the periodic table. Elements in the same group have similar chemical properties.
• Periods: Horizontal rows. Properties change as you move across a period.

Understanding where an element is on the periodic table can tell you a lot about its reactivity and properties, including its potential as a reducing or oxidizing agent.

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in its gaseous state. It is an important concept in chemistry as it influences the chemical behavior and reactivity of elements.

Elements with low ionization energy tend to lose electrons easily. These elements are usually metals, found on the left side of the periodic table. They are often good reducing agents because they can donate electrons to other substances.

• Group 1 elements have the lowest ionization energies, making them highly reactive metals.
• The ionization energy increases as you move across a period from left to right.

So, when considering reducing agents, look for elements with low ionization energy since they easily lose electrons and reduce other substances.

Electron Affinity

Electron affinity measures the change in energy when an atom gains an electron. It indicates how eager an atom is to accept an electron.

Elements with high electron affinity are generally non-metals, located on the right side of the periodic table. These elements gain electrons easily, but this makes them poor reducing agents because their tendency is to gain rather than lose electrons.

• Halogens like chlorine (Cl) and fluorine (F) have high electron affinities, making them effective oxidizing agents rather than reducing agents.
• Electron affinity generally increases as you move across a period from left to right.

Therefore, while high electron affinity helps in gaining electrons, it is not a desirable trait for a reducing agent.

Alkali Metals

Alkali metals belong to Group 1 of the periodic table. This group includes elements like lithium (Li), sodium (Na), and potassium (K).

These elements are highly reactive, primarily due to their single electron in the outermost shell, which they readily lose to achieve a stable electron configuration.

• They have low ionization energies.
• Their reactivity increases down the group as the atom size increases, making it easier to lose the outer electron.

Due to these properties, alkali metals are excellent reducing agents. Sodium (Na) is a prime example, often used in chemistry when a strong reducing agent is required.