Which of the following best explains why metallic character increases from right to left across a period in the periodic table?

• A. Elements on the right have lower ionization energies, making them more metallic.
• B. Elements on the left have fewer valence electrons, making it easier for them to lose electrons and form positive ions.
• C. Elements on the right have larger atomic radii, which increases their metallic character.
• D. Elements on the left have higher electronegativity, which increases their metallic character.

Answer: (B)

Verified step by step guidance

1. Recall that metallic character refers to how readily an element can lose electrons to form positive ions (cations). Metals tend to lose electrons easily, while nonmetals tend to gain electrons.
2. Understand that as you move from right to left across a period, the number of valence electrons decreases. Elements on the left side have fewer valence electrons, which means they can lose electrons more easily to achieve a stable electron configuration.
3. Consider ionization energy, which is the energy required to remove an electron from an atom. Ionization energy generally decreases from right to left across a period, making it easier for elements on the left to lose electrons and exhibit metallic behavior.
4. Note that atomic radius decreases from left to right across a period, so elements on the right have smaller atomic radii, not larger. Therefore, the statement about larger atomic radii increasing metallic character on the right is incorrect.
5. Recognize that electronegativity increases from left to right across a period, so elements on the right are more electronegative and less metallic. Hence, higher electronegativity on the left does not explain increased metallic character.