Question

In the modern periodic table, what trend is observed in the atomic radius in a period and why is it so?

Answer 1

• The atomic size decreases from left to right in a period (horizontal row) of the current periodic table.
• Reason:
  • Over time, the amount of protons, or nuclear charge, increases.
  • Since electrons are added to the same shell, shielding is not greatly increased.
  • The same-shell electrons are drawn closer to the nucleus by a stronger nuclear force, which decreases atomic size.