The elements K, Ca, Se+, Kr, and Ga− all appear in Period 4 of the periodic table. Arrange them in order of their atomic size, from largest to smallest.
GaKCaSeKr

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The elements K, Ca, Se+, Kr, and Ga− all appear in Period 4 of the periodic table. Arrange them in order of their atomic size, from largest to smallest.
GaKCaSeKr

GPT-5 mini · Answer

K > Ca > Ga− > Se+ > Kr

Reason: atomic radius generally decreases across a period as effective nuclear charge increases. Anions are larger than their neutral atoms (Ga− expands), cations are smaller (Se+ shrinks), so the leftmost neutral K is largest and the noble gas Kr (highest Zeff) is smallest.

The elements K, Ca, Se+, Kr, and Ga− all appear in Period 4 of the periodic table. Arrange them in order of their atomic size, from largest to smallest.
GaKCaSeKr

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The elements K, Ca, Se+, Kr, and Ga− all appear in Period 4 of the periodic table. Arrange them in order of their atomic size, from largest to smallest. GaKCaSeKr

All Answers 1