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Multiple Choice
Which noble gas is used as the core in the noble gas electron configuration of iodine?
A
Kr (krypton)
B
Ar (argon)
C
Ne (neon)
D
Xe (xenon)
Verified step by step guidance
1
Identify the atomic number of iodine, which is 53. This tells us iodine has 53 electrons in its neutral state.
Recall that noble gas electron configurations use the electron configuration of the nearest noble gas with fewer electrons as a shorthand 'core' to simplify the notation.
List the noble gases and their atomic numbers: Ne (10), Ar (18), Kr (36), Xe (54). We want the noble gas with the largest atomic number less than 53.
Compare the atomic numbers: Ne (10) < 53, Ar (18) < 53, Kr (36) < 53, Xe (54) > 53. Since Xe has more electrons than iodine, it cannot be the core.
Conclude that krypton (Kr), with 36 electrons, is the noble gas used as the core in the noble gas electron configuration of iodine.