Answer:
To achieve <u>the stable noble gas configuration</u>
Explanation:
According to the octet rule, chemical elements tend to bond in order to <u>complete their valence shell and attain the stable noble gas configuration: ns² np⁶. Thus elements tend to lose, share or gain electrons to have eight electrons in their valence shell.</u>
Alkali metals are the reactive chemical elements that belong to the group 1 of the periodic table. The <u>general electron configuration of alkali metals is ns¹.</u>
So alkali metals tend to l<u>ose the valence electron</u> to form a monovalent cation or positively charged ion and <u>achieve the stable noble gas configuration.</u>
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Halogens are the reactive chemical elements that belong to the group 17 of the periodic table. The <u>general electron configuration of halogens is ns² np⁵.</u>
So halogens tend to <u>gain one electron </u>to form a monovalent anion or negatively charged ion and <u>achieve the stable noble gas configuration.</u>
<u>Therefore, </u><u>halogens and alkali metals</u><u> are the reactive elements that tend to lose one valence electron and gain one electron, respectively, to form </u><u>ions</u><u> and </u><u>achieve the stable noble gas configuration.</u>