Which electrons in a calcium atom in the ground state have the greatest effect on the chemical prope

June 2018 NY Regents Chemistry Exam

4 Which electrons in a calcium atom in the ground state have the greatest effect on the chemical properties of calcium?
(1) the two electrons in the first shell
(2) the two electrons in the fourth shell

(3) the eight electrons in the second shell

(4) the eight electrons in the third shell

Solution: Valence electrons (electrons in the outermost shell) have he greatest effect on the chemical properties of an element. Looking on the Periodic Table, we see the electron configuration for calcium is 2-8-8-2 (2 electrons in the first shell, 8 in the second shell, 8 in the third shell and 2 in the fourth shell). The fourth shell is the outermost shell and has two electrons.

Answer: 2

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