Can someone answer this chemistry question regarding Alkali metals?

Question

I don't know but can you explaing why the Alkali metals form cations having a charge of +1 when they react.

My other question is why Halogens form anions having a charge of -1 when they react

Thank you

Answer 1

All the atoms of alkali metals only have a single electron in its valence shell. All the atoms of halogens have 7 electrons in its valence shell. Based on Octet Rule see the link I provided), atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas.
Hence, atoms of alkali metals are prone to loose the single electron, to form cations having a charge of +1 when they react. Atoms of halogens are prone to gain 1 more electron, to form anions having a charge of -1 when they react.