Question

Four elements are shown. The elements shown are carbon, atomic number 6 and atomic mass 12.01, sulfur, atomic number 16 and atomic mass 32.07, helium, atomic number 2 and atomic mass 4.00, and chlorine, atomic number 17 and atomic mass 35.45. Use the periodic table to choose the most stable element. A. Carbon B. Sulfur C. Helium D. Chlorine

Answer 1

Helium

A stable element is an element that has a complete no. of electrons in its outer shell.

Carbon has only 4 electrons in its last shell (to be a stable element its meant to have 8)

sulfur has 6 electrons in its last shell (to be a stable element, its meant to have 8 electrons)

chlorine has 7 electrons in its last shell (to be stable, its meant to have 8)

whereas Helium has 2 electrons in its last and only shell. ( Helium has only one electron shell as it's period number in the periodic table is 1. and the first electron shell can only hold 2 electrons, whereas the second electron shell can only hold 8 and so on.)