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JAMB Chemistry 1989 Question 7

Question 7

Periodic Table

The atomic radius of Li, Na and K are 1.33A, 1.54A and 1.96A respectively. Which of the following explains this gradation in atomic radius?

  1. A.Electropositivity decreases from Li to Na to K
  2. B.Electronegativity decreases from Li to Na to K.
  3. C.The number of electron shells increases from Li to Na to K.
  4. D.The elements are in the same period.
Show the answer and explanation

Answer: C (The number of electron shells increases from Li to Na to K.)

Explanation

Going down group 1, each element has one more shell of electrons (Li 2 shells, Na 3, K 4), so the atoms get bigger.