Why metallic character decreases and non metallic character increases on moving from left to right in a periodic table?

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Metallic and Non-metallic Character in Periodic Table

Metallic and non-metallic character are the two properties that change as we move across the periodic table from left to right.

Metallic Character

Metallic character refers to the ability of an element to lose electrons and form positive ions. As we move from left to right in the periodic table, the metallic character decreases. This is due to the following reasons:

Decrease in atomic size: As we move from left to right in the periodic table, the atomic size decreases. This is because the number of protons in the nucleus increases, leading to a stronger attraction between the nucleus and the valence electrons. This makes it difficult for the valence electrons to be removed and hence, the metallic character decreases.

Increase in effective nuclear charge: The effective nuclear charge increases as we move from left to right in the periodic table. This is because the number of protons in the nucleus increases while the number of inner electrons remains the same. This leads to a stronger attraction between the nucleus and the valence electrons, making it difficult for them to be removed and hence, decreasing the metallic character.

Decrease in electron shielding: As we move from left to right in the periodic table, the number of valence electrons remains the same while the number of protons in the nucleus increases. This leads to a decrease in electron shielding, which is the ability of inner electrons to shield the valence electrons from the attraction of the nucleus. This makes it difficult for the valence electrons to be removed and hence, decreases the metallic character.

Non-metallic Character

Non-metallic character refers to the ability of an element to gain electrons and form negative ions. As we move from left to right in the periodic table, the non-metallic character increases. This is due to the following reasons:

Increase in effective nuclear charge: The effective nuclear charge increases as we move from left to right in the periodic table. This is because the number of protons in the nucleus increases while the number of inner electrons remains the same. This leads to a stronger attraction between the nucleus and the valence electrons, making it easier for them to be gained and hence, increasing the non-metallic character.

Increase in electron affinity: The electron affinity is the energy released when an atom gains an electron. As we move from left to right in the periodic table, the electron affinity increases. This is because the effective nuclear charge increases, making it easier for the atom to attract electrons and release energy. This leads to an increase in non-metallic character.

Increase in electronegativity: Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. As we move from left to right in the periodic table, the electronegativity increases. This is because the effective nuclear charge increases, making it easier for the atom to attract electrons. This leads to an increase in non-metallic character.

Answer

This happens because as we move from left to right in periodic table elements electronegativity increases Hence there tendency to lose electron decrease and tendencyto gain electron increases hence their metallic character decreases

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