CHEMICAL PROPERTIES OF HALOGENS.

Let us study ions of halogens. Electronic affinity is not very high in fluorine as it is supposed. It is because of the high electronic repulsion which is higher than in other halogens as chlorine of bromine, because of the little size of fluorine atom.

 Ions of halogens form typical ionic compounds when they bond with alkali metals and with alkaline metals.

When we solve this compounds in water, they have ion dipole interaction with water molecules.

 Let us study chemical properties of halogens.

CHEMICAL PROPERTIES OF HALOGENS.

Let us study direct chemical reactions. Reactivity falls from fluorine to iodine. The high reactivity of fluorine molecule is because of its low dissociation energy. In fact, fluorine molecule reacts violently with hydrogen in low temperature, fluorine reacts directly with metals in exothermic reactions and platinum and gold are attacked by fluorine.

Chlorine is not as reactive as fluorine. It reacts with all the no metals except carbon, nitrogen and oxygen. So if we want to obtains compounds with this elements and chlorine, we will have to work with indirect chemical reactions.

Talking about the reactivity of chlorines with metals, we have to say that chlorine reacts with alkali metals, with alkaline metals, and with aluminum very easy (velocity of reaction is high). To combine chlorine with transition metals, we have to heat.

 Dry chlorine is very inert, so it is perfect to transport chorine inside receptacles made of iron.

Activity of bromine and iodine is very low.

Percentage of covalent bond grow up from fluorine ion to iodine ion because of polarizability of halogen is bigger when atomic volume is bigger.

Let us study reactions in water.

Halogens are oxidants but its oxidant power decrease from fluorine to chlorine. If we talk about fluorine and chlorine, its oxidizing power, in low values of pH, is bigger than oxidizing power oxygen has.

X₂ + H₂O = 2 X^1- + 2 H¹⁺ + ½ O₂.

Attending to a thermodynamic point of view, bromine and iodine have to react in the same way as fluorine and chlorine, but the kinetic of the reaction is slow.

Talking about oxidizing power halogens have, fluorine oxides to chlorine, chlorine oxides to bromine, and so and so.

2 Br^1- +  Cl₂ = Br₂ + 2 Cl^1-.

2 I^1- +  Br₂ = I₂ + 2 Br^1-.

Chlorine does not oxide permanganate (oxidizing powerful of permanganate is bigger), so it is a good method to obtain chlorine.

Cl^1- + MnO₄^1- -> Mn²⁺ + Cl₂.