Question

select all that apply
which statements about the chemical stability of atoms is true?
fluorine is stable when its outer energy level has seven electrons.
sulfur is stable when its outer energy level has eight electrons.
hydrogen is stable when its outer energy level has two electrons.
group 15 elements are stable when their outer energy levels have five electrons.
group 17 elements are stable when their outer energy levels have eight electrons.

Explanation:

• Fluorine: Fluorine is in Group 17. Atoms are stable when their outer - energy level (valence shell) has 8 electrons (except for hydrogen and helium). Fluorine has 7 valence electrons. It is not stable when its outer energy level has 7 electrons.
• Sulfur: Sulfur is in Group 16. It is stable when its outer energy level has 8 electrons (octet rule).
• Hydrogen: Hydrogen follows the duet rule. It is stable when its outer energy level (1s) has 2 electrons.
• Group 15 elements: Group 15 elements have 5 valence electrons. They are stable when they gain 3 electrons to complete the octet (8 electrons in the outer energy level).
• Group 17 elements: Group 17 elements have 7 valence electrons. They are stable when they gain 1 electron to have 8 electrons in their outer energy level (octet rule).

Answer:

Hydrogen is stable when its outer energy level has two electrons.