Question

Name the smallest atom of the third period.

Answer 1

1. In the period table, the third period has 8 elements- Sodium (Na), Magnesium (Mg), Aluminum (Al), Silicon (Si), Phosphorus (P), Sulfur (S), Chlorine (Cl), and Argon (Ar).
2. Atomic size across a period: As we move across a period from left to right, there is an addition of a proton in the nucleus, and the extra electron added goes to the same shell. Thus, due to the more number of protons, the electrons are attracted more strongly toward the nucleus leading to a decrease in the atomic size.
3. Hence, the smallest atom of the third period is Argon (on the extreme right of the periodic table).