1. Reaction with Metals: When chlorine gas comes into contact with certain metals, such as sodium, the metal atoms transfer their outermost electron to chlorine atoms. This results in the formation of positively charged metal ions (e.g., $Na^+$) and negatively charged chloride ions ($Cl^-$). For example:
$$2Na + Cl_2 → 2NaCl$$
In this reaction, each chlorine atom gains one electron from sodium, becoming a chloride ion.
2. Reaction with Hydrogen: Chlorine gas can also react with hydrogen gas ($H_2$) to produce hydrogen chloride gas ($HCl$). During this reaction, each chlorine atom gains one electron from a hydrogen atom, forming a chloride ion. The overall reaction is:
$$H_2 + Cl_2 → 2HCl$$
3. Reaction with Other Reducing Agents: Chlorine gas can undergo reduction reactions with various reducing agents, such as sulfites ($SO_3^{2-}$), thiosulfates ($S_2O_3^{2-}$), or metal hydrides (e.g., sodium borohydride, $NaBH_4$), leading to the formation of chloride ions.
In these reactions, the reducing agents donate electrons to chlorine atoms, causing them to gain an extra electron and become chloride ions.
Overall, the formation of chloride ions with a 1- charge occurs when chlorine atoms accept an electron from another atom or molecule, reducing their neutral state to a negatively charged state.
