Which element gains two electrons to fill its outermost energy level?
(1 point)
Responses
selenium (Se)
magnesium (Mg)
fluorine (F)
lithium (Li)
The element that gains two electrons to fill its outermost energy level is fluorine (F).
To determine the answer, we need to look at the electron configuration of each element. The electron configuration of an atom describes the distribution of its electrons in energy levels or shells.
Fluorine (F) has an atomic number of 9, which means it has 9 electrons. The electron configuration of fluorine is 1s² 2s² 2p⁵. The outermost energy level of fluorine is the second energy level (2p shell), and it has 7 valence electrons.
To fill its outermost energy level and achieve a stable electron configuration, fluorine needs to gain one more electron. By gaining one electron, it will have 8 valence electrons, which corresponds to a full or stable outermost energy level.
However, the question asks for an element that gains two electrons. Therefore, fluorine gains one more electron to satisfy the octet rule and forms an anion with a charge of -1.
Out of the given options, none of the other elements gain two electrons to fill their outermost energy level. Selenium (Se) gains two electrons to complete its outermost energy level, magnesium (Mg) loses two electrons to achieve a stable configuration, and lithium (Li) loses one electron to fill its outermost energy level.
Hence, the correct answer is fluorine (F).