Chemistry · Periodic trends in properties of elements: atomic and ionic radii, ionization enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity
Assertion Atomic size decreases in a period due to increase of atomic number. Re
Assertion Atomic size decreases in a period due to increase of atomic number. Reason The nuclear charge is increasing and size of valence shell remains same as we move from left to right. Hence, in any period, the atomic size of the element decreases from left to right.
- A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
- C. Assertion is correct but Reason is incorrect
- D. Both Assertion and Reason are incorrect
Step-by-step solution
As we move left to right in a period, the atomic number increases, which increases nuclear charge. Electrons are added to the same valence shell, so the effective nuclear charge increases, pulling the electrons closer to the nucleus. Thus atomic size decreases. The reason correctly explains this trend.