August 2019 NY Regents Chemistry Exam
5 Which electron shell in an atom of calcium in the ground state has an electron with the greatest amount of energy?
(1) 1
(2) 2
(3) 3
(4) 4
Solution: The further electrons are located from the nucleus, the greater is their amount of energy. We can locate calcium on the Periodic Table and see that its' electron configuration is 2-8-8-2. This means it has 2 electrons in the first shell, 8 in the second shell, 8 in the third shell and 2 in the fourth shell. The last electrons shell must have an electron with the greatest amount of energy. In this case, this is shell number 4.
Answer: 4
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