Define reducing power and explain its trend in the periodic table.

Part 1: Reducing agents:

• A reducing agent is one of the reactants of the redox reaction which reduces the other reactant by giving out electrons to the reactant.
• s-block elements are good reducing agents.
• The reducing agent after losing electrons gets oxidized and also causes the opposite reactant to get reduced by supplying electrons.
• Reducing agents are electropositive in nature.
• For example,$\mathrm{Li},\mathrm{Na},\mathrm{K}$ etc.

Part 2: Reducing power:

• Reducing power is defined as the potential or power of any substance to reduce another substance.
• That can be either by addition or removal of hydrogen or by loss or gain of electrons.

Part 3: Trends in the periodic table:

• On moving down the group, the reducing power increases because from top to bottom atomic size increases, due to this attraction between the nucleus and valence electron increases that allowing the element to lose electrons more easily and therefore increasing its reducing power.
• In a period, from left to right in a horizontal row of the periodic table, the atomic size decreases and the nuclear charge increases, so the electron affinity and ionization energy both increase.
• Therefore, the tendency to lose electrons decreases across the period from left to right, and thus the reducing property also decreases across the period from left to right.