Which electron configuration represents the electrons of an atom in an excited state?

August 2018 NY Regents Chemistry Exam

32 Which electron configuration represents the electrons of an atom in an excited state? (1) 2-5

(2) 2-8-5

(3) 2-5-1

(4) 2-6

Solution: In an atom the first shell can hold a maximum of 2 electrons, the second shell holds a maximum of 8 and the third holds a maximum of 8. Electrons in an excited state have moved from lower energy level to the higher energy level. We can see that in 2-5-1 electron configuration, an electron moved from the second energy level to the third. Otherwise, we would see 2-6 since the second energy level has a maximum of 8 electrons.

Answer: 3

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