If atoms of a halogen nonmetal gain one electron, the atoms then have how many valence electrons?
Answer (3)
Don't all halogens have 8 valence electrons? They don't need to gain or lose any because they are already stable.
Halogens in Group 17, like fluorine and chlorine, have seven valence electrons. By gaining one electron, they form 1- charged ions with an octet of electrons in their valence shell, matching the stable electron configuration of the next noble gas.
When atoms of a halogen nonmetal gain one electron, they achieve a stable electron configuration by completing their valence shell with eight electrons, following the octet rule. Halogens, which are elements from Group 17 (Group 7A) of the periodic table, such as fluorine, chlorine, bromine, and iodine, all have seven valence electrons in their natural state.
For instance, a fluorine atom, which already has seven valence electrons, would find it more energetically favorable to gain one electron rather than losing seven to achieve a stable octet.
Therefore, when halogens gain one electron, they form anions (negatively charged ions) with a 1- charge. If we consider chlorine as an example, when it gains one electron, chlorine attains a total of eight electrons in its valence shell, thus becoming a chloride ion (Cl-). In this state, chlorine has the same electron configuration as argon, the next noble gas in the periodic table.
This principle applies to all halogen elements (Group 17), where the gain of one electron results in the formation of a halide ion with an octet of electrons. For example, the formula of the resulting ion when a fluorine atom gains one electron is F-.
Halogen atoms have 7 valence electrons. When they gain one electron, they achieve 8 valence electrons, forming a negatively charged ion known as a halide ion. This configuration gives them stability similar to the nearest noble gas.
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