Chemistry – The Periodic Table - Arrangement of elements | e-Consult

As you move from left to right across period 3 (Na to Ar), the metallic character decreases. This is because the atoms become smaller, and their ionization energies increase. Here's a detailed explanation:

• Atomic Size: Atomic size decreases across a period. This is due to increasing nuclear charge, which pulls the electrons closer to the nucleus.
• Ionization Energy: Ionization energy is the energy required to remove an electron from an atom. As atomic size decreases, the valence electrons are held more tightly by the nucleus. Therefore, it requires more energy to remove an electron, meaning the ionization energy increases.
• Metallic Bonding: Metallic bonding involves delocalised electrons. Metallic character is related to the ease with which electrons can be delocalised. As ionization energy increases, it becomes more difficult for electrons to be delocalised, weakening the metallic bond. This leads to a decrease in metallic character.

In summary, the decreasing atomic size and increasing ionization energy across period 3 result in a weaker metallic bond and a reduced ability to delocalise electrons, hence a decrease in metallic character.